CP3 Modifications You Can Do Yourself!
#1
09-15-2007, 11:28 AM
CP3 Modifications You Can Do Yourself!
CP3 Modifications you can do yourself!
Many thanks to Relentless Diesel
This should help some of you understand how to modify your own CP3 injector pump. We'll get into more detail of CP3's in another article, but for now understand that all you can do is completely fill the plungers with fuel. The CP3 has three plungers and each plunger intakes a certain amount of fuel and expels it into the fuel rail with each injector pump revolution.
Each plunger makes the same length downward and upward stroke on each revolution regardless of how much fuel is commanded. If the plungers were full of fuel the pump would always move the same amount of fuel per revolution and we know that's not true. At light throttle/low power the pump moves very little fuel into the rail. At high power levels the pump moves all the fuel it can.
It's easy to see that the plungers are not always full of fuel on the intake stroke. Our goal as pump modifiers is to make sure the plungers are more full of fuel (therefore moving more fuel into the rail) during high power levels than the stock pump.
There are several restrictions from the time the fuel enters to the CP3 until it gets sucked into the plunger/barrel chamber. As we eliminate each restriction the plunger chamber can fill more completely with fuel.
This article will cover two simple modifications that most anyone can do to increase the fuel delivery from their CP3 pump.
Take a look at the picture below. You'll notice two easily removable pieces bolted to the back of the CP3.
On the lower right you'll see the fuel control actuator (FCA) which has the black colored electrical connector attached to it. You'll also notice the aluminum housing of the gear pump on the very back. Both of these items are easily removed with the pump still in the truck and cause major restriction to fuel flow.
Remove the FCA first. It will look something like this.
Start with an extremely clean work place.
Using an allen wrench or a cutoff screwdriver pry out the endcap. (We used a torx bit for the pictures, but it deforms the i.d. of the endcap too excessively.)
Many thanks to Relentless Diesel
This should help some of you understand how to modify your own CP3 injector pump. We'll get into more detail of CP3's in another article, but for now understand that all you can do is completely fill the plungers with fuel. The CP3 has three plungers and each plunger intakes a certain amount of fuel and expels it into the fuel rail with each injector pump revolution.
Each plunger makes the same length downward and upward stroke on each revolution regardless of how much fuel is commanded. If the plungers were full of fuel the pump would always move the same amount of fuel per revolution and we know that's not true. At light throttle/low power the pump moves very little fuel into the rail. At high power levels the pump moves all the fuel it can.
It's easy to see that the plungers are not always full of fuel on the intake stroke. Our goal as pump modifiers is to make sure the plungers are more full of fuel (therefore moving more fuel into the rail) during high power levels than the stock pump.
There are several restrictions from the time the fuel enters to the CP3 until it gets sucked into the plunger/barrel chamber. As we eliminate each restriction the plunger chamber can fill more completely with fuel.
This article will cover two simple modifications that most anyone can do to increase the fuel delivery from their CP3 pump.
Take a look at the picture below. You'll notice two easily removable pieces bolted to the back of the CP3.
On the lower right you'll see the fuel control actuator (FCA) which has the black colored electrical connector attached to it. You'll also notice the aluminum housing of the gear pump on the very back. Both of these items are easily removed with the pump still in the truck and cause major restriction to fuel flow.
Remove the FCA first. It will look something like this.
Start with an extremely clean work place.
Using an allen wrench or a cutoff screwdriver pry out the endcap. (We used a torx bit for the pictures, but it deforms the i.d. of the endcap too excessively.)
The following 5 users liked this post by Whit:
bigdaddydiesel (08-28-2008),
Diesel Dawgs Performance (10-21-2007),
Erickbruck (08-28-2015),
kslb7 (04-06-2009),
WinstonWolf (08-28-2008)
#2
09-15-2007, 11:29 AM
Carefully remove the spring and lightly tap the fca on the table to help slide the metering valve out. (Use extreme caution when handling the metering valve. If it is bent or even scratched it can stick will be useless.)
All the fuel that is allowed to enter the plungers must first make it through these two tiny triangular holes in this valve.
Each triangle is 0.110" high
and 0.068" wide
for a total area of 0.00748 square inches between the two. This is equivalvent to a single hole with a diameter of 0.097".
By enlarging these triangles more fuel will be able to get to the plungers. This is the smallest restriction from the inlet of the CP3 all the way into the plunger chamber.
We've tried various shapes which allow more or less flow at each duty cycle (position) of the valve and the one that works the best also happens to be the easiest to machine.
A simple dremel tool cutoff wheel can be used to perform a simple slice into the triangle.
**It is extremely important that you do not modify the tip of the triangle. The tip is crucial to the valves ability to stop and regulate fuel at small flowrates (idling, cruising, etc.)**
All the fuel that is allowed to enter the plungers must first make it through these two tiny triangular holes in this valve.
Each triangle is 0.110" high
and 0.068" wide
for a total area of 0.00748 square inches between the two. This is equivalvent to a single hole with a diameter of 0.097".
By enlarging these triangles more fuel will be able to get to the plungers. This is the smallest restriction from the inlet of the CP3 all the way into the plunger chamber.
We've tried various shapes which allow more or less flow at each duty cycle (position) of the valve and the one that works the best also happens to be the easiest to machine.
A simple dremel tool cutoff wheel can be used to perform a simple slice into the triangle.
**It is extremely important that you do not modify the tip of the triangle. The tip is crucial to the valves ability to stop and regulate fuel at small flowrates (idling, cruising, etc.)**
The following 4 users liked this post by Whit:
bigdaddydiesel (08-28-2008),
Diesel Dawgs Performance (10-21-2007),
just killing um (01-27-2013),
kslb7 (04-06-2009)
#3
09-15-2007, 11:29 AM
Use some gloves or something soft for protection. I don't want to hear complaints that you cut your finger. Don't chuck it up in a vise because you'll damage the valve. BE CAREFUL!!!
Here's an example of a cut valve.
You'll need to spend a LOT of time polishing the cut edges both inside and outside with some very fine sand paper. The valve will need to freely slide in and out of the housing without force. If you get in a hurry and force a valve into the housing with a burr of any kind it will scratch the housing and be JUNK. Throw it away and start over.
Now take a look at the spring and endcap that you pryed out. Remember they stack like this:
You can enlarge the center hole in the endcap, but there's really no use going bigger than 0.130" since that is the I.D. of the spring. Fuel has to travel down the center of the spring on its way out of the FCA.
Again, I cannot stress deburring all edges with sandpaper and cleanliness enough. You don't have the luxury of a filter to catch your mistakes. What you leave behind goes directly into the pump plungers and then into your $350 a piece injectors.
Insert the valve, spring and press the endcap back into place and you're finished modifying your FCA.
For those of you that want to understand the FCA a little better before modifying it, we have included some cross sectional views to simply it.
Here is the housing cut open.
Here is a closer view. Look at the first darkened region (left to right). You'll notice two holes. There are four holes total and this is where the fuel enters this valve.
Here is a picture with the valve in place positioned to delver NO FUEL!
Here's an example of a cut valve.
You'll need to spend a LOT of time polishing the cut edges both inside and outside with some very fine sand paper. The valve will need to freely slide in and out of the housing without force. If you get in a hurry and force a valve into the housing with a burr of any kind it will scratch the housing and be JUNK. Throw it away and start over.
Now take a look at the spring and endcap that you pryed out. Remember they stack like this:
You can enlarge the center hole in the endcap, but there's really no use going bigger than 0.130" since that is the I.D. of the spring. Fuel has to travel down the center of the spring on its way out of the FCA.
Again, I cannot stress deburring all edges with sandpaper and cleanliness enough. You don't have the luxury of a filter to catch your mistakes. What you leave behind goes directly into the pump plungers and then into your $350 a piece injectors.
Insert the valve, spring and press the endcap back into place and you're finished modifying your FCA.
For those of you that want to understand the FCA a little better before modifying it, we have included some cross sectional views to simply it.
Here is the housing cut open.
Here is a closer view. Look at the first darkened region (left to right). You'll notice two holes. There are four holes total and this is where the fuel enters this valve.
Here is a picture with the valve in place positioned to delver NO FUEL!
The following 3 users liked this post by Whit:
#4
09-15-2007, 11:29 AM
Here is a picture with the valve in place to deliver FULL FUEL FLOW!
This final picture shows all three parts in place!
For those of you thinkers out there who think the inlet holes might be a restriction themselves. Here's the math.
Each hole is only 0.100" but since there are four of them the equivalent hole size is 0.200". MUCH larger than the 0.130" endcap on the other end.
The next restriction we will tackle is the orifices in the gear pump housing.
The gear pump looks like this once it's removed.
The red arrows are pointing to where two aluminum rivets will be. Flip the pump over to have the front side facing upwards and drill out both rivets.
Once you've removed the rivets, you can separate the front pump cover from the gears and rear housing.
The two red arrows here are inlet and outlet ports which can be enlarged. The outlet port is around 0.110" if memory serves me correctly. You can easily enlarge both holes to the 0.140"-0.160" range.
Flow will still be restricted by the 0.130" endcap in the FCA so there's no reason to go overboard here.
Obviously, you'll need to deburr the holes and clean everything up. You can use a 6-32 machine screw from any hardware store to bolt the pump back together if you don't have a rivet gun.
That should do it. Sit back and enjoy the fact that in under an hour you were able to perform the same modifications that some shops charge over $1100 to do.
This final picture shows all three parts in place!
For those of you thinkers out there who think the inlet holes might be a restriction themselves. Here's the math.
Each hole is only 0.100" but since there are four of them the equivalent hole size is 0.200". MUCH larger than the 0.130" endcap on the other end.
The next restriction we will tackle is the orifices in the gear pump housing.
The gear pump looks like this once it's removed.
The red arrows are pointing to where two aluminum rivets will be. Flip the pump over to have the front side facing upwards and drill out both rivets.
Once you've removed the rivets, you can separate the front pump cover from the gears and rear housing.
The two red arrows here are inlet and outlet ports which can be enlarged. The outlet port is around 0.110" if memory serves me correctly. You can easily enlarge both holes to the 0.140"-0.160" range.
Flow will still be restricted by the 0.130" endcap in the FCA so there's no reason to go overboard here.
Obviously, you'll need to deburr the holes and clean everything up. You can use a 6-32 machine screw from any hardware store to bolt the pump back together if you don't have a rivet gun.
That should do it. Sit back and enjoy the fact that in under an hour you were able to perform the same modifications that some shops charge over $1100 to do.
The following 4 users liked this post by Whit:
bigdaddydiesel (08-28-2008),
Diesel Dawgs Performance (10-21-2007),
Pupcreek (06-05-2014),
torrencial (06-17-2009)
#8
11-11-2007, 02:37 PM
From the manual
FUEL SYSTEM
A Robert Bosch high-pressure fuel injection pump is used. The pump is attached to the back of the timing gear housing at the left /front side of the engine
DESCRIPTION
The fuel system on the 5.9L Common Rail Diesel Engine uses a rotary mechanical fuel injection pump and an Electronic Control Module (ECM) and is a drive-by-wire system, meaning there is no physical throttle cable.
The fuel delivery system consists of the:
- Accelerator pedal position-sensor module
- Air cleaner housing\element
- Fuel filter\water separator
- Fuel temperature sensor
- Fuel heater
- Fuel rail pressure relief valve
- Fuel rail pressure sensor
- Fuel injection pump
- Fuel injectors
- Fuel tank
- Fuel tank filler\vent tube assembly
- Fuel tank filler-tube cap
- Fuel tank module containing the electric lift pump, roll-over valve and a fuel gauge sending unit (fuel level sensor).
- Fuel tubing\lines\hoses
- High-pressure fuel injector lines
- Low-pressure fuel supply and return lines
- Low-pressure fuel return line
- Overflow valve
- Quantity control Fuel Control Actuator valve
- Quick-connect fittings
- Water sensor\drain module
FUEL INJECTION PUMP
The Cummins 5.9L CRD uses the Bosch CP3 injection pump, used also on the DMax 6.6L V8 CRD and the Jeep 2.8L CRD
DESCRIPTION
A radial, 3-piston pump, with a gearotor pump attached to the back, is used as the high-pressure pump for common-rail fuel pressure generation - in this system it is capable of pressures between 300-1600 bar (4351-23206 psi) .
A spring-loaded Cascade Overflow Valve regulates internal housing pressure
Regulated internal housing pressure is oem-specific
The pump shaft is driven by the timing belt at 1:1 ratio to the crankshaft.
Fuel pressure is generated independently of the injection process.
A Fuel Control Actuator solenoid valve regulates injection pressure
The pump is lubricated by the pumped Diesel fuel and is not responsible for fuel injection timing.
OPERATION
GEAROTOR PUMP
DESCRIPTION
The gearotor pump has two functions
- draws fuel from the fuel supply
- increases fuel pressure for regulation to housing pressure required for internal lubrication and supplying the high-pressure injection pump
OPERATION
This fuel system uses a gearotor supply-pump attached to the rear of the high-pressure pump. This medium-pressure fuel pump is driven by the end of the high-pressure pump shaft, and can generate 20" vacuum at the fuel inlet at high rpm.
The gearotor pump is supplied fuel from the lift pump in the fuel tank through the fuel manager\filter.
The outlet of the gearotor pump provides pressurized fuel to a branched circuit internal to the high-pressure pump flange, which supplies both the Fuel Control Actuator solenoid valve and the Cascade Overflow Valve\regulator. Because the gearotor pump increases fuel flow and pressure as engine rpm increases, the pressure and flow is regulated by the COV.
The COV and gearotor supply-pump are not serviced independently of the high-pressure pump.
CASCADE OVERFLOW VALVE
DESCRIPTION
The COV is located on the front cover of the high pressure pump.
The Cascade Overflow Valve has three functions:
- regulation of lubrication fuel to the internal moving parts of the high-pressure pump
- regulation of the fuel pressure being supplied to the Fuel Control Actuator solenoid valve
- return excess fuel to the fuel tank
This regulated internal pressure, known as housing pressure, is determined by engine displacement and power requirements - the 5.9L CRD requires 5-12.4 bar (80-180 psi)
For comparison, the 2.8L 4-cyl Jeep CRD requires 5bar maximum (73psi)
OPERATION
The COV has a spring-loaded center spool-piece that has a drilled channel with three passages: one for initial low-pressure lubrication, one for lubrication at housing-pressure , and one for overflow. The valve is operated in three stages based on the level of pressure at the inlet.
Stage 1
When the fuel pressure entering the tip of the COV is between 0 and 3 bar (43psi), pressure is too low to overcome regulator spring tension and fuel flows through the center channel, only . This passage always allows fuel flow through to the pump center-ring and lubricates the pump bushings and internal moving parts. This circuit also allows air to bleed during initial cranking and returns the air to the fuel tank.
The COV is in Stage 1 during cranking, only.
Stage 2
When the fuel entering the COV exceeds 5bar (73psi), but is less than 12.4bar (180psi), the spool-piece moves against spring tension aligning a second passage for lubrication purposes.
Stage 2 can be reached during cranking and initial start up.
Stage 3
When fuel pressure exceeds 12.4bar (180psi), the spool-piece aligns with the overflow passage. This stage relieves the pressure into an overflow circuit that sends the fuel back to the inlet side of the gearotor pump, thus limiting maximum fuel pressure to 12.4bar (180psi).
Lubrication fuel continues to flow through all channeled passages during this stage.
Excess fuel is sent back to the fuel tank through the fuel-return circuit
Stage 3 is reached at over-pressure
FUEL CONTROL ACTUATOR
DESCRIPTION
The Fuel Control Actuator solenoid valve is located on the back of the front cover of the high-pressure pump. The solenoid is pulse-width modulated by the ECM and meters the amount of fuel that flows into the high-pressure elements inside the high-pressure pump.
The solenoid is inactive up to 30 seconds after IGNition switch is initially keyed to ON position to allow maximum fuel pressure to the fuel rail during cranking and start up. ECM assumes FCA valve control when CPS signal and rail pressure are within acceptable limits
OPERATION
The Fuel Control Actuator solenoid valve is a pulse-width modulated valve that controls the amount of fuel sent or delayed to the high-pressure pump elements inside the high-pressure pump. The ECM determines the fuel pressure set point based on engine sensor and rail-pressure inputs. If the actual fuel-rail pressure is too low, the ECM commands the solenoid to allow more fuel to flow to the high-pressure pump. This minimizes the difference between the actual fuel-rail pressure reading and the set point. The ECM will also operate the solenoid to delay fuel, reducing flow-rate, if the fuel-rail pressure becomes too high.
The FCA valve is commanded open by the ECM to allow the high-pressure pump to build maximum pressure (1600bar, 23,206psi), or closed to reduce rail pressure.
Thus, rail fuel-pressure can be increased or decreased independent of engine speed
High Pressure Pumping Plungers
The FQS valve supplies three high pressure pumping chambers. The pumping chambers have one-way inlet valves that allow fuel to flow into the chambers. The valves then close as the fuel is compressed, causing the high pressure fuel to overcome a spring-loaded ball-and-seat outlet valve.
All three pumping chambers are tied together in one circuit internal to the pump and provide high pressure fuel between 300bar (4351psi) and 1600bar (23,206psi) through a steel line to the fuel rail.
The pump is driven at 1:1 engine speed and is not responsible for injection timing.
Pump function is to provide fuel at high-pressure, while the ECM controls injection pressure and timing.
FUEL RAIL
DESCRIPTION
The fuel rail is mounted to the cylinder-head cover\intake manifold. The rail distributes regulated high-pressure fuel equally to the fuel injectors.
A pressure sensor is screwed into the rail so ECM can read and regulate system pressure.
A pressure valve is screwed into the fuel rail to allow regulated overflow return to the fuel tank.
OPERATION
The fuel rail stores the fuel for the injectors at high pressure. At the same time, the pressure oscillations which are generated due to the high-pressure pump delivery and the injection of fuel are dampened by rail volume.
The fuel rail is common to all cylinders, hence it’s name "common rail". Even when large quantities of fuel are extracted, the fuel rail maintains a constant inner pressure. This ensures that injection pressure remains constant from the instant the injector opens to the end of the injection event.
PRESSURE LIMITING VALVE
DESCRIPTION
The fuel pressure limiting valve is located on the top of the fuel rail.
OPERATION
Fuel pressure at the fuel rail is monitored by the fuel rail pressure sensor. If fuel pressure becomes excessive, the high pressure fuel overcomes a spring-loaded plunger with tapered-seat outlet valve, causing the pressure limiting valve to open and vent excess pressure into the fuel drain circuit, and back to the fuel tank.
FUEL SYSTEM
A Robert Bosch high-pressure fuel injection pump is used. The pump is attached to the back of the timing gear housing at the left /front side of the engine
DESCRIPTION
The fuel system on the 5.9L Common Rail Diesel Engine uses a rotary mechanical fuel injection pump and an Electronic Control Module (ECM) and is a drive-by-wire system, meaning there is no physical throttle cable.
The fuel delivery system consists of the:
- Accelerator pedal position-sensor module
- Air cleaner housing\element
- Fuel filter\water separator
- Fuel temperature sensor
- Fuel heater
- Fuel rail pressure relief valve
- Fuel rail pressure sensor
- Fuel injection pump
- Fuel injectors
- Fuel tank
- Fuel tank filler\vent tube assembly
- Fuel tank filler-tube cap
- Fuel tank module containing the electric lift pump, roll-over valve and a fuel gauge sending unit (fuel level sensor).
- Fuel tubing\lines\hoses
- High-pressure fuel injector lines
- Low-pressure fuel supply and return lines
- Low-pressure fuel return line
- Overflow valve
- Quantity control Fuel Control Actuator valve
- Quick-connect fittings
- Water sensor\drain module
FUEL INJECTION PUMP
The Cummins 5.9L CRD uses the Bosch CP3 injection pump, used also on the DMax 6.6L V8 CRD and the Jeep 2.8L CRD
DESCRIPTION
A radial, 3-piston pump, with a gearotor pump attached to the back, is used as the high-pressure pump for common-rail fuel pressure generation - in this system it is capable of pressures between 300-1600 bar (4351-23206 psi) .
A spring-loaded Cascade Overflow Valve regulates internal housing pressure
Regulated internal housing pressure is oem-specific
The pump shaft is driven by the timing belt at 1:1 ratio to the crankshaft.
Fuel pressure is generated independently of the injection process.
A Fuel Control Actuator solenoid valve regulates injection pressure
The pump is lubricated by the pumped Diesel fuel and is not responsible for fuel injection timing.
OPERATION
GEAROTOR PUMP
DESCRIPTION
The gearotor pump has two functions
- draws fuel from the fuel supply
- increases fuel pressure for regulation to housing pressure required for internal lubrication and supplying the high-pressure injection pump
OPERATION
This fuel system uses a gearotor supply-pump attached to the rear of the high-pressure pump. This medium-pressure fuel pump is driven by the end of the high-pressure pump shaft, and can generate 20" vacuum at the fuel inlet at high rpm.
The gearotor pump is supplied fuel from the lift pump in the fuel tank through the fuel manager\filter.
The outlet of the gearotor pump provides pressurized fuel to a branched circuit internal to the high-pressure pump flange, which supplies both the Fuel Control Actuator solenoid valve and the Cascade Overflow Valve\regulator. Because the gearotor pump increases fuel flow and pressure as engine rpm increases, the pressure and flow is regulated by the COV.
The COV and gearotor supply-pump are not serviced independently of the high-pressure pump.
CASCADE OVERFLOW VALVE
DESCRIPTION
The COV is located on the front cover of the high pressure pump.
The Cascade Overflow Valve has three functions:
- regulation of lubrication fuel to the internal moving parts of the high-pressure pump
- regulation of the fuel pressure being supplied to the Fuel Control Actuator solenoid valve
- return excess fuel to the fuel tank
This regulated internal pressure, known as housing pressure, is determined by engine displacement and power requirements - the 5.9L CRD requires 5-12.4 bar (80-180 psi)
For comparison, the 2.8L 4-cyl Jeep CRD requires 5bar maximum (73psi)
OPERATION
The COV has a spring-loaded center spool-piece that has a drilled channel with three passages: one for initial low-pressure lubrication, one for lubrication at housing-pressure , and one for overflow. The valve is operated in three stages based on the level of pressure at the inlet.
Stage 1
When the fuel pressure entering the tip of the COV is between 0 and 3 bar (43psi), pressure is too low to overcome regulator spring tension and fuel flows through the center channel, only . This passage always allows fuel flow through to the pump center-ring and lubricates the pump bushings and internal moving parts. This circuit also allows air to bleed during initial cranking and returns the air to the fuel tank.
The COV is in Stage 1 during cranking, only.
Stage 2
When the fuel entering the COV exceeds 5bar (73psi), but is less than 12.4bar (180psi), the spool-piece moves against spring tension aligning a second passage for lubrication purposes.
Stage 2 can be reached during cranking and initial start up.
Stage 3
When fuel pressure exceeds 12.4bar (180psi), the spool-piece aligns with the overflow passage. This stage relieves the pressure into an overflow circuit that sends the fuel back to the inlet side of the gearotor pump, thus limiting maximum fuel pressure to 12.4bar (180psi).
Lubrication fuel continues to flow through all channeled passages during this stage.
Excess fuel is sent back to the fuel tank through the fuel-return circuit
Stage 3 is reached at over-pressure
FUEL CONTROL ACTUATOR
DESCRIPTION
The Fuel Control Actuator solenoid valve is located on the back of the front cover of the high-pressure pump. The solenoid is pulse-width modulated by the ECM and meters the amount of fuel that flows into the high-pressure elements inside the high-pressure pump.
The solenoid is inactive up to 30 seconds after IGNition switch is initially keyed to ON position to allow maximum fuel pressure to the fuel rail during cranking and start up. ECM assumes FCA valve control when CPS signal and rail pressure are within acceptable limits
OPERATION
The Fuel Control Actuator solenoid valve is a pulse-width modulated valve that controls the amount of fuel sent or delayed to the high-pressure pump elements inside the high-pressure pump. The ECM determines the fuel pressure set point based on engine sensor and rail-pressure inputs. If the actual fuel-rail pressure is too low, the ECM commands the solenoid to allow more fuel to flow to the high-pressure pump. This minimizes the difference between the actual fuel-rail pressure reading and the set point. The ECM will also operate the solenoid to delay fuel, reducing flow-rate, if the fuel-rail pressure becomes too high.
The FCA valve is commanded open by the ECM to allow the high-pressure pump to build maximum pressure (1600bar, 23,206psi), or closed to reduce rail pressure.
Thus, rail fuel-pressure can be increased or decreased independent of engine speed
High Pressure Pumping Plungers
The FQS valve supplies three high pressure pumping chambers. The pumping chambers have one-way inlet valves that allow fuel to flow into the chambers. The valves then close as the fuel is compressed, causing the high pressure fuel to overcome a spring-loaded ball-and-seat outlet valve.
All three pumping chambers are tied together in one circuit internal to the pump and provide high pressure fuel between 300bar (4351psi) and 1600bar (23,206psi) through a steel line to the fuel rail.
The pump is driven at 1:1 engine speed and is not responsible for injection timing.
Pump function is to provide fuel at high-pressure, while the ECM controls injection pressure and timing.
FUEL RAIL
DESCRIPTION
The fuel rail is mounted to the cylinder-head cover\intake manifold. The rail distributes regulated high-pressure fuel equally to the fuel injectors.
A pressure sensor is screwed into the rail so ECM can read and regulate system pressure.
A pressure valve is screwed into the fuel rail to allow regulated overflow return to the fuel tank.
OPERATION
The fuel rail stores the fuel for the injectors at high pressure. At the same time, the pressure oscillations which are generated due to the high-pressure pump delivery and the injection of fuel are dampened by rail volume.
The fuel rail is common to all cylinders, hence it’s name "common rail". Even when large quantities of fuel are extracted, the fuel rail maintains a constant inner pressure. This ensures that injection pressure remains constant from the instant the injector opens to the end of the injection event.
PRESSURE LIMITING VALVE
DESCRIPTION
The fuel pressure limiting valve is located on the top of the fuel rail.
OPERATION
Fuel pressure at the fuel rail is monitored by the fuel rail pressure sensor. If fuel pressure becomes excessive, the high pressure fuel overcomes a spring-loaded plunger with tapered-seat outlet valve, causing the pressure limiting valve to open and vent excess pressure into the fuel drain circuit, and back to the fuel tank.
The following users liked this post:
bigdaddydiesel (08-28-2008)
#9
11-11-2007, 02:37 PM
FUEL LINES
DESCRIPTION
LOW-PRESSURE FUEL LINES
All fuel lines up to the fuel injection pump are considered low-pressure. This includes the fuel lines from the fuel tank module to the inlet of the high-pressure fuel injection pump. The fuel-return lines and the fuel-drain lines are also considered low-pressure lines.
High-pressure lines are used between the fuel injection pump and the fuel injectors
HIGH PRESSURE FUEL LINES
High-pressure fuel lines are used between the high pressure fuel injection pump and the fuel rail, and between the fuel rail and fuel injectors
All other fuel lines are considered low-pressure lines.
OPERATION - HIGH PRESSURE FUEL LINES
High-pressure fuel lines deliver fuel under extremely high pressure - between 300-1600 bar (4351-23206 psi) - from the high-pressure pump to the rail to the fuel injectors. The lines expand and contract from the high-pressure fuel pulses generated during the injection process, which can delay the injection event - ECM compensates for that based on component specs
All high-pressure fuel lines between the rail and the injectors are of the same length and inside diameter to ensure equal-duration injection events, cylinder to cylinder.
Correct high-pressure fuel line usage and installation is critical to smooth engine operation.
FUEL MANAGER\FILTER
FUEL FILTER / WATER SEPARATOR
DESCRIPTION
The fuel filter/water separator assembly is located on left side of engine above the starter motor. The assembly also
includes the fuel heater, Water-In-Fuel (WIF) sensor and a screened banjo bolt attached at the bottom of the fuel
filter canister.
OPERATION
The fuel filter/water separator protects the fuel injection pump by removing water and contaminants from the fuel.
The construction of the filter/separator allows fuel to pass through it, but helps prevent moisture (water) from doing
so.
Moisture precipitates out and collects at the bottom of the canister.
A screened banjo-bolt is attached to the filtered outlet at the bottom of the fuel filter canister to provide additional filtering for the high pressure fuel system components.
A Water-In-Fuel (WIF) sensor is attached to the lower side of fuel filter housing.
A fuel heater is installed into the top of the filter/separator housing.
WATER IN FUEL SENSOR
DESCRIPTION
The Water-In-Fuel (WIF) sensor is located on the side of the fuel filter/water separator canister.
OPERATION
The sensor varies an input to the Engine Control Module (ECM) when it senses water in the fuel filter/water separator.
As the water level in the filter/separator increases, the resistance across the WIF sensor decreases. This
decrease in resistance is sent as a signal to the ECM and compared to a standard reference value. Once the value
drops to 30 to 40 kilohms, the ECM will activate the water-in-fuel warning lamp through CCD bus circuits. This all
takes place when the ignition key is initially put in the ON position. The ECM continues to monitor the input while the engine is running.
FUEL HEATER
DESCRIPTION
The fuel heater assembly is located on the side of the fuel filter housing and internal to the fuel filter housing .
The heater/element assembly is equipped with a temperature sensor (thermostat) that senses fuel temperature. This
sensor is attached to the fuel heater/element assembly.
OPERATION
The fuel heater is used to prevent diesel fuel from waxing during cold weather operation.
When the fuel temperature is below 45° ±8 F (7°C), the temperature sensor allows current to flow to the heater
element warming the fuel. When the fuel temperature is above 75° ±8 F (24°C), the sensor stops current flow to the
heater element.
Battery voltage to operate the fuel heater element is supplied from the ignition switch and through a solid state
device in the IPM.
There is no Fuel Heater Relay - fuel heater element and solid-state device in IPM are not ECM controlled.
The heater element operates on 12 volts, 300 watts at 0° F (-18° C).
The fuel heater is used to prevent diesel fuel from waxing during cold weather operation.
A malfunctioning fuel heater can cause a wax build-up in the fuel filter/water separator. Wax build-up in the filter/
separator can cause engine starting problems and prevent the engine from revving up. It can also cause blue or
white fog-like exhaust. If the heater is not operating in cold temperatures, the engine may not operate due to fuel
waxing.
The fuel heater assembly is located on the side of fuel filter housing and internal to the fuel filter housing.
The heater assembly is equipped with a built-in fuel temperature sensor (thermostat) that senses fuel temperature.
When fuel temperature drops below 45° ± 8° F (7° C), the sensor allows current to flow to built-in heater element
to warm fuel. When fuel temperature rises above 75 °± 8° F (24° C), the sensor stops current flow to heater element
(circuit is open).
Voltage to operate fuel heater element is supplied from ignition switch, through the solid-state device in IPM, to fuel
temperature sensor and on to fuel heater element.
The heater element operates on 12 volts, 300 watts at 0 °F (-18° C). As temperature increases, power requirements
decrease.
A minimum of 7 volts is required to operate the fuel heater. The resistance value of the heater element is less than
1 ohm (cold) and up to 1000 ohms warm
FUEL TRANSFER PUMP
ELECTRIC FUEL LIFT PUMP
DESCRIPTION
The fuel transfer pump (fuel lift pump) is part of the fuel pump module.
The fuel pump module is located in the fuel tank.
The 12–volt electric pump is operated and controlled by the Engine Control Module (ECM).
The ECM controls a relay in the Intelligent Power Module (IPM) for transfer pump operation.
OPERATION
The purpose of the fuel transfer pump is to supply (transfer) a low-pressure fuel source fromthe fuel tank through
the fuel filter/water separator tothe high-pressure fuel injection pump.
Check valves within the pump control direction of fuel flow and prevent fuel bleed-back during engine shut down.
Maximum current flow to the pump is 5 amperes.
With the engine running, the pump has a 100 percent duty-cycle.
The transfer pump is self-priming: when the key is first turned on (without cranking engine), the pump will operate
for approximately 2 seconds and then shut off (Note: When ambient temperatures are cold enough to cause the
intake air heaters to operate, the fuel lift pump will operate during the entire intake air pre-heat cycle). The pump will
also operate for up to 25 seconds after the starter is engaged, and then stop if the engine is not running.
A safety feature ensures the pump shuts off immediately if the key is on and the engine stops running.
The fuel volume of the transfer pump will always provide more fuel than the fuel injection pump requires. Excess
fuel is returned from the injection pump through an overflow valve, and then back to the fuel tank.
DESCRIPTION
LOW-PRESSURE FUEL LINES
All fuel lines up to the fuel injection pump are considered low-pressure. This includes the fuel lines from the fuel tank module to the inlet of the high-pressure fuel injection pump. The fuel-return lines and the fuel-drain lines are also considered low-pressure lines.
High-pressure lines are used between the fuel injection pump and the fuel injectors
HIGH PRESSURE FUEL LINES
High-pressure fuel lines are used between the high pressure fuel injection pump and the fuel rail, and between the fuel rail and fuel injectors
All other fuel lines are considered low-pressure lines.
OPERATION - HIGH PRESSURE FUEL LINES
High-pressure fuel lines deliver fuel under extremely high pressure - between 300-1600 bar (4351-23206 psi) - from the high-pressure pump to the rail to the fuel injectors. The lines expand and contract from the high-pressure fuel pulses generated during the injection process, which can delay the injection event - ECM compensates for that based on component specs
All high-pressure fuel lines between the rail and the injectors are of the same length and inside diameter to ensure equal-duration injection events, cylinder to cylinder.
Correct high-pressure fuel line usage and installation is critical to smooth engine operation.
FUEL MANAGER\FILTER
FUEL FILTER / WATER SEPARATOR
DESCRIPTION
The fuel filter/water separator assembly is located on left side of engine above the starter motor. The assembly also
includes the fuel heater, Water-In-Fuel (WIF) sensor and a screened banjo bolt attached at the bottom of the fuel
filter canister.
OPERATION
The fuel filter/water separator protects the fuel injection pump by removing water and contaminants from the fuel.
The construction of the filter/separator allows fuel to pass through it, but helps prevent moisture (water) from doing
so.
Moisture precipitates out and collects at the bottom of the canister.
A screened banjo-bolt is attached to the filtered outlet at the bottom of the fuel filter canister to provide additional filtering for the high pressure fuel system components.
A Water-In-Fuel (WIF) sensor is attached to the lower side of fuel filter housing.
A fuel heater is installed into the top of the filter/separator housing.
WATER IN FUEL SENSOR
DESCRIPTION
The Water-In-Fuel (WIF) sensor is located on the side of the fuel filter/water separator canister.
OPERATION
The sensor varies an input to the Engine Control Module (ECM) when it senses water in the fuel filter/water separator.
As the water level in the filter/separator increases, the resistance across the WIF sensor decreases. This
decrease in resistance is sent as a signal to the ECM and compared to a standard reference value. Once the value
drops to 30 to 40 kilohms, the ECM will activate the water-in-fuel warning lamp through CCD bus circuits. This all
takes place when the ignition key is initially put in the ON position. The ECM continues to monitor the input while the engine is running.
FUEL HEATER
DESCRIPTION
The fuel heater assembly is located on the side of the fuel filter housing and internal to the fuel filter housing .
The heater/element assembly is equipped with a temperature sensor (thermostat) that senses fuel temperature. This
sensor is attached to the fuel heater/element assembly.
OPERATION
The fuel heater is used to prevent diesel fuel from waxing during cold weather operation.
When the fuel temperature is below 45° ±8 F (7°C), the temperature sensor allows current to flow to the heater
element warming the fuel. When the fuel temperature is above 75° ±8 F (24°C), the sensor stops current flow to the
heater element.
Battery voltage to operate the fuel heater element is supplied from the ignition switch and through a solid state
device in the IPM.
There is no Fuel Heater Relay - fuel heater element and solid-state device in IPM are not ECM controlled.
The heater element operates on 12 volts, 300 watts at 0° F (-18° C).
The fuel heater is used to prevent diesel fuel from waxing during cold weather operation.
A malfunctioning fuel heater can cause a wax build-up in the fuel filter/water separator. Wax build-up in the filter/
separator can cause engine starting problems and prevent the engine from revving up. It can also cause blue or
white fog-like exhaust. If the heater is not operating in cold temperatures, the engine may not operate due to fuel
waxing.
The fuel heater assembly is located on the side of fuel filter housing and internal to the fuel filter housing.
The heater assembly is equipped with a built-in fuel temperature sensor (thermostat) that senses fuel temperature.
When fuel temperature drops below 45° ± 8° F (7° C), the sensor allows current to flow to built-in heater element
to warm fuel. When fuel temperature rises above 75 °± 8° F (24° C), the sensor stops current flow to heater element
(circuit is open).
Voltage to operate fuel heater element is supplied from ignition switch, through the solid-state device in IPM, to fuel
temperature sensor and on to fuel heater element.
The heater element operates on 12 volts, 300 watts at 0 °F (-18° C). As temperature increases, power requirements
decrease.
A minimum of 7 volts is required to operate the fuel heater. The resistance value of the heater element is less than
1 ohm (cold) and up to 1000 ohms warm
FUEL TRANSFER PUMP
ELECTRIC FUEL LIFT PUMP
DESCRIPTION
The fuel transfer pump (fuel lift pump) is part of the fuel pump module.
The fuel pump module is located in the fuel tank.
The 12–volt electric pump is operated and controlled by the Engine Control Module (ECM).
The ECM controls a relay in the Intelligent Power Module (IPM) for transfer pump operation.
OPERATION
The purpose of the fuel transfer pump is to supply (transfer) a low-pressure fuel source fromthe fuel tank through
the fuel filter/water separator tothe high-pressure fuel injection pump.
Check valves within the pump control direction of fuel flow and prevent fuel bleed-back during engine shut down.
Maximum current flow to the pump is 5 amperes.
With the engine running, the pump has a 100 percent duty-cycle.
The transfer pump is self-priming: when the key is first turned on (without cranking engine), the pump will operate
for approximately 2 seconds and then shut off (Note: When ambient temperatures are cold enough to cause the
intake air heaters to operate, the fuel lift pump will operate during the entire intake air pre-heat cycle). The pump will
also operate for up to 25 seconds after the starter is engaged, and then stop if the engine is not running.
A safety feature ensures the pump shuts off immediately if the key is on and the engine stops running.
The fuel volume of the transfer pump will always provide more fuel than the fuel injection pump requires. Excess
fuel is returned from the injection pump through an overflow valve, and then back to the fuel tank.
#10
12-16-2007, 01:41 PM
To all DMAX owners who are reading this thread:
I just realized that the metering valve shown in this write-up is from a Cummins CP3 and has the triangle ports. The DMAX doesnt have triangle ports, it has rectangle ports.
WARNING...DO NO SCREW UP THOSE RECTANGLE PORTS!!! There are no replacement parts to be had over the counter so if you make a mistake you will either be buying a new CP3 or begging a shop to find you a plunger without raping you.
I just realized that the metering valve shown in this write-up is from a Cummins CP3 and has the triangle ports. The DMAX doesnt have triangle ports, it has rectangle ports.
WARNING...DO NO SCREW UP THOSE RECTANGLE PORTS!!! There are no replacement parts to be had over the counter so if you make a mistake you will either be buying a new CP3 or begging a shop to find you a plunger without raping you.
