Bosch VE Pump Operation
 

Overview

The injection pump is a single-plunger mechanical pump which meters and distributes fuel to the injectors in the correct firing order. The pump is driven by the camshaft spur belt or gear at one-half crankshaft speed. All moving parts inside the pump are lubricated by diesel fuel, so the pump is maintenance-free; diesel pumps operate reliably for a long time if clean fuel is used.

Attachment 54025

Idle speed, maximum speed, and injection timing can be adjusted with workshop equipment; the stop solenoid can be replaced, the fuel delivery valve body can be replaced, but any internal problem means replacement of the pump.

Fuel Delivery Valves

The fuel delivery valves on the injection pump help ensure that the injector will close quickly at the end of each injection. The injectors must close quickly in order to prevent fuel "dribble" which can cause pre-ignition and high exhaust emissions.

At the start of injection the delivery valve is lifted off of its seat and pressurized fuel flows to the injector:

Attachment 54026

At the end of injection the delivery valve moves to the closed position. A column of fuel is now trapped in the injection line:

Attachment 54027

The force of the spring will push the valve back further onto its seat and the trapped column of fuel now expands. The sudden drop in pressure caused by the expanding fuel, allows the injector to snap shut and eliminate and fuel "dribble":

Attachment 54028

Vane Pump

The rotary-vane pump inside the injection pump draws fuel through the filter from the tank and supplies it to the distributor plunger.

The vane pump rotor is driven by the engine camshaft spur belt or gear. As the rotor spins, centrifugal force holds the vanes against the walls of the pressure chamber. The off-center or eccentric layout of the rotor and pressure chamber "squeezes" fuel trapped between the vanes and forces it out the delivery port.

Attachment 54029

Vane pump delivery pressure is between 3-7 bar depending on the engine speed and is controlled by the regulating valve.

Vane pump fuel pressure lubricates moving parts in the rest of the pump, supplies fuel to the distributor plunger for the injectors, and controls injection timing advance mechanism.

Injection pump manufacturers use a special test "bench" to set and check internal pump pressures. The vane pump and distributor plunger injection pressures cannot be checked easily with normal workshop equipment.

If clean fuel is used, diesel injection pumps operate reliably for a long time. Diesel pumps should not be disassembled or "adjusted." Normal shop work consists only of troubleshooting to determine whether a pump might need replacement.

Injection & Distribution

The injection pump driveshaft turns the vane pump, distributor plunger, and cam plate as a unit.

Springs hold the cam plate and distributor plunger against stationary rollers - in this way, the plunger also moves back and forth as it turns:

Attachment 54030

Whenever an intake port in the plunger is in line with the filling port in the pump body, fuel from the vane pump fills the pressure chamber.

As the plunger turns, the intake port is covered up so that fuel is trapped in the pressure chamber. Now, the cam plate and rollers push the plunger and pressurize the fuel to about 1800 psi.:

Attachment 54031

As the plunger continues to turn, the outlet port in the plunger lines up with the injection passage in the pump body, opening the check valve and supplying high-pressure fuel to the injector.

The injection ports in the pump are arranged so the injectors receive fuel in the cylinder firing sequence:

Attachment 54032

Metering Fuel

The amount of fuel injected is controlled by changing the injection cut-off point according to engine speed and load conditions.

The injection cut-off point is controlled by the position of a metering sleeve on the distributor plunger. The metering sleeve usually covers a relief port in the plunger. Uncovering the relief port stops injection.

The position of the metering sleeve is controlled by a linkage connected to a centrifugal governor and also the accelerator pedal.

Metering Fuel - Starting

When the engine is not running, the leaf spring presses the starting lever to the left so that the metering sleeve moves to the right.

The distributor plunger must move further before the relief port is exposed. Injection lasts longer so that more fuel is supplied during starting:

Attachment 54033

Metering Fuel - Idle

At idle speed, the weights in the centrifugal governor are partly expanded so that governor sleeve move to the right. The starting lever is pushed against the control lever so that the metering sleeve moves to the left.

The distributor plunger now moves a shorts distance before the relief port is uncovered. Injection lasts a short time fo that a small amount of fuel is supplied at idle:

Attachment 54017

The injection pump automatically compensates for effects of temperature and load changes at idle. When idle speed begins to drop, the centrifugal governor weights and the governor sleeve retract; the idle spring then pushes the metering sleeve to the right, increasing the amount of fuel to correct the idle speed.

Metering Fuel - Acceleration

During acceleration, the control lever is pulled to the left by the linkage from the accelerator pedal.

The metering sleeve is moved to the right so that more fuel is injected before the relief port in uncovered. Engine speed increases until the movemnt of the governor "neutralizes" the effect of the pedal linkage:

Attachment 54018

Metering Fuel - Maximum Speed

With the pedal linkage at "full load," engine speed increases to about 5400 rpm. At this point, the governor is spinning with enough centrifugal force for the governor sleeve to "stretch" the governor spring and force the control lever to the right.

Attachment 54019

The metering sleeve moves far enough to the left to uncover the relief port at the beginning of the distributor plunger stroke. There is no pressure for injection until engine speed drops and the metering sleeve moves to the right again.

This provision acts as a speed limiter and is designed to react slowly enough so that engine performance simply "flattens out" at the top limit.

Injection Timing Advance

Near the end of each compression stroke, diesel fuel is injected directly into the combustion chamber. Injection must continue well past piston TDC in order to burn the necessary amount of fuel to provide engine power.

As engine speed increases, stroke timing becomes shorter and injection timing becomes longer. Burning must begin sooner to ensure that peak combustion pressures still occur at the most efficient point after TDC.

Diesel injection timing is advanced by a hydraulic piston in the injection pump:

Attachment 54020

As engine speed increases, fuel pressure from the vane pump also increases. Vane pump pressure pushes the injection advance piston to the left against the spring so that the roller housing turns slightly.

Since the cam plate is turning in the opposite direction, the "ramps" on the cam plate engage the roller sooner whenever the injection advance piston moves to the left. This means that the distributor plunger beings injection sooner.

The injection timing advance piston is located in the bottom of the injection pump body:

Attachment 54021

The only cold start and warm-up device necessary for the diesel fuel system is a control which advances injection timing at idle and during low speed running.

A lever turns a cam which pushes the hydraulic piston to the left. This advances injection time about 5 degrees.

Attachment 54022

This injection advance provides more time for the fuel to burn, which improves performance and prevents smoking during cold starts and warm-up.

The cold start cam does not advance the complete range of injection timing. Above 2200 rpm, the piston operates normally and does not contact the cam:

Attachment 54023

Injection Timing

Since diesel fuel ignites in the hot compressed air as soon as injection begins, injection timing is as important as gasoline engine spark timing.

Attachment 54024

The actual moment of injection cannot be checked easily because it is affected not only by the injection advance mechanism but also by the exact opening pressure of each injector.

Thanks To Jimbo486 @ DTR for this!

Bobby, who the @%#$ is gonna read all that?

:poak:

I read it. Nice pictures. Needs an AFC section. :pca1:


Do our KSB's have a cam on the timing piston like that? The one I took apart had no such lever, but it wasn't a pick-up application.

I am inpressed with the detail and find it very helpfull thanks.

Rock On Bud, good work.:U:

i think i deserve to be given credit when credit is due. i spent a decent amount of time scanning all those images and typing everything from my fuel injection handbook when i studied and became certified in diesel technology. i think someone forgot to give credit when this was posted here. here's where the write-up originates and where every member would tell you that i wrote it. should be pretty obvious too....

http://www.dieseltruckresource.com/d....html?t=231914

you're welcome

me! :jump:

Awesome post, anybody know where to get all the specks for a complete rebuild?

Under "Metering fuel-Maximum speed" is the"5400 RPM" a typo?

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Thank you!:tu:

thanks good info and hopefully it will be somewhere where i can read it again and again thick skull takes awhile to sink in:w2:

great write up :tu: to whoever posted it and to the guy that wrote it:jump:

VE Bosch injection pump functioning
 

Very good, useful and complete description, for us all, to better understand how that pump works. Tks.

One question: I have one of these pumps for my 6 cilinders naturally aspirated engine.

In the oil & water refrigerator circuit there is a device called "cold start device" which function is to improve performance of the engine at low rpm and at start.

In my engine, a RD28 Nissan, there is a water circuit that cross that device, I suppose to warm it up or to activate it when the engine is just starting, when it is cold.

For reasons I don+t know, they sold me the engine with that device shunted, I mean, water does not circulate for the cold start device and goes directly to the oil cooler device.

This may be affecting the engine performance at low rpm's according to yr article. Am I right?

I want to connect that circuit, but don´t know the circulation direction. Maybe it is not relevant? What do you think?

The cold start assembly is instaled in the VE Bosch pump.

If you are familiar with this kind of engine may answer my question right away. But if not, I may scan the circuit images and send them to you.

This engine is a 6 in line, 2.8 liters.

Thank you in advance,

OldBeaver

(New to the forum, this is my first post)

The "cold start device" installed on our VE's don't involve water or oil temperature; it's electronically controlled and turned on according to an intake air temperature sensor.

I'm really interested in what you have on yours. This is what the Dodges have.


Attachment 48356

Attachment 48357

Attachment 48358

to my knowledge, cold starts were only put on military vehicles, they were a devise that had a canister of fuel that would ignite and warm up the intake air.

I have really only seen those things on Detroit's and the AVDS1790 Tank.

not sure if tis is what you are talking about.

@cummins guy:
That was (and still used) method to preheat the chamber.
This is a cold start aid and different from the KSB.( more like the glow plugs and grid heater)



There are several ways possible to gain advance during cold start :

- the electric KSB (as desrcibed above)
- the manual (old fashioned) KSB with a wire that actuates a lever to adjust advance and idle speed (typical in VW engines from 86 to 92)
- the automatic wax expansion chamber which adjusts advance acording to coolant temperature using the expanding wax chamber to adjust a lever and advance.

all methods interfere at the same point and act in the same way.

@Oldbeaver:
Direction of the flow should be directed from the hot engine through the wax chamber.
It's a device typically seen in the beginning of the 90's.

It's interesting to hear that the RD 28 (Nissan Patrol)has a VP pump. Over here in europe this engine has a Denso license built Bosch inline pump.

Dear Beagle1,

I am trying to attach pictures of the circuits of the cold start device from the manual, as well as a picture of the device itself.

Hope I can paste them here.

I couldn't.

Will upload them to a site.

Old Beaver

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Here are some pictures to show how this device is located in the RD28 diesel engine:

http://www.flickr.com/photos/oldbeaver/4446411674/
This is the cold start device:
http://farm3.static.flickr.com/2762/...bccb7a1ace.jpg

and these are the complementary pictures.

Forgive me for not being able to arrange the pictures as well as Beagle1 !

http://farm5.static.flickr.com/4070/...59b23083f8.jpg
http://farm5.static.flickr.com/4007/...1240cba837.jpg
http://farm3.static.flickr.com/2768/...d7198a9569.jpg
http://farm5.static.flickr.com/4007/...1240cba837.jpg

From the pictures, It seems that the cold start device has an actuator to make some change in the injection process. But I cannot say what is the action the cold start device makes. At present, it is not connected, I mean, water is not circulating through it.

What do you think?

Old Beaver

is the RD2 engine made by Isuzu?

RD28 engine
 

Hey Cummins Guy,

I don't know about the RD2 engine.

But the RD28 engine I have is made by Nissan.

OldBeaver :hellox:

remember isuzu makes engines for lots of other companys(like duracraps for GM)

what does the crew do on the top right of the first pic

Great post, I found this post via google.

I'm looking for some info on the electronically controlled mechanical injection pump, VE Covec-F, but would not post here since it's a Dodge thread

My tread: https://www.dieselbombers.com/passen...pump-work.html

Meeeeeee
 

Yes, MEEE. Firstly thanks goes to Bobby.. That was one hell of a post. I now know how my pump works.:jump: I have had hell with mine, but okay now.:rocking: Also as his post say; it will help me greatly in thefuture, and anyone else that read it. I just had to join the forum hope to find lots more like this. :c:Cheers guys. Pete.

IP delivery issue... help please
 

Hello out there-

new to the forum... got a head scratcher here i cant seem to figure out, hoping someone here can give me some insight.

Have a 93 ford medium duty (f600) with a turbo/ intercooled 5.9. Im having some issues with the injection pump (its a ve rotary, not an inline).

Problem started a couple days ago... the truck seemed to run out of fuel. It however was NOT out of fuel. My first chck was the lift pump, it was working just fine and putting out a healthy 7psi.

Second, i changed the fuel filter- just on principle, it had been a little while.

Next i primed the fuel system, and bled the injectors. It fired up without much trouble and will stay running for the most part.

However- its missing consistantly on one cylender (#6 right at the back).

After some searching, i have found the the injection pump is not suplying any fuel to this cylender- or at least, nearly none- and not enough to fire the injector.

When the teuck is running, i can crack the lines on each of the other injectors and get a nice spray of diesel, but when i crack #6 i get nearly nothing.

I have also removed the line from the back of the pump itself and also get nothing.

The other cylenders seem to be running normaly, so im inclined to thank that the pump is still ok for the most part... perhaps the delivery valve for #6 is not opening properly?

I know there are lots of guys on this forum smarter than me- lets hear your thoughts.

This is a work truck, need to get it going asap!

Thx in advance for your replies- Andy

If you value your pump, and don't want a big bill for smashed things, get the pump seen to straight away. I'm only an owner who came here looking for ideas on a problem that I have, but if something is adrift inside...oh the pain.

Similar post a month back, his would only stay running with #6 cracked.
I suspect air was getting into the system and crack #6 bled it off, without cracking #6 the air built up and got into the other lines. #6 is at the top of the pump. As usual if he fixed it he did not give any feed back.
Common deal here, never feedback when the issue is resolved.

By what you are saying you have some fuel but not a lot at #6.
Either air or a blockage

Yes- thats exactally whats happening to mine.

I have found that i can keep it running nearly forever with #6 cracked. Once i tighten it back down it seems to runo allright for a while, but once i rev the motor it stops firing and eventually cavitates the pump.

Im a little bit puzzled- if it were a blockage in the pump, or a delivery valve issue, i could understand why the injector quits firing.... but that dosent explain the air does it (or am i missing somthing?).

If it is an air intrusion in the system... would that allways affect #6 first? Wouldnt it airlock all of the injectors? Thats what usually happens if you simply run out of fuel.

A good idea is to replace fuel hose with clear vinyl tubing in low pressure parts of the system, this will tell you a lot, as it has for me. Doesn't need to be reinforced. In a rotary VE pump I cant imagine how could air could into only one injector line but who knows.

Neither can i. Thats why im so confused.

an air intrusion would occour only between the tank and the lift pump, correct?


I do have a theory (but im not sure it really makes any sense...) is it possible that, if somthing in the pump is preventing fuel delivery to the #6 injector- the injector is allowing compression air (from cylender #6) back through the line and forcing its way into the pump, causing it to cavitate?

Im just spitballing here...

I'm fairly sure that the air getting into my IP was coming from a split in a perished section of rubber tube in the injector overflow drain line. I can blame the injection guy for this as when he overhauled my injectors he didn't use the correct tube - the manufacture's tube is z-shaped, my injector guy used bent-up straight fuel tube. Because of the way Isuzu set the fuel system up, injector overflow moves through a three-way banjo junction BACK to the IP inlet, and not straight back to the tank. So it's NOT true that air can only get in between your lift pump (which in the case of the Bosch VE is an in-built vane pump) and your tank. Incidentally I found that very few people (including the guy who overhauled my IP almost a year ago) understand how the CSD (Cold Start Device) which is an integral part of the fuel setup in this truck actually works. It's the opposite to how people imagine it works.