My 2004 Dodge Ram with 250K miles ate a second fuel pump a couple weeks ago. Fuel pouring out of the pump, truck died, P0148 code (low/no fuel rail pressure). And so I pulled the old pump and installed a rebuilt one.

Of course the truck still won't start. I pulled the two supply lines from the pump - one is supply, the other is a return line - and cranked the engine. Lots of fuel out of one line, nothing from the other. Supply pressure is 10 lbs with the lines on. Next I took the common rail high pressure line loose, pointed it away from the engine, and cranked again - nothing, not a drop of fuel is getting pumped. I called Huckstorf; they suggested unplugging the regulator electrical connection; this made no difference.

I assume either the rebuilt pump is bad or the nut that holds the pump shaft to the drive gear is slipping (unlikely but I'll check later). So I have two questions:

1) Of the two lines from the fuel canister to the pump which is the supply and which is the return? Amazingly I can find nothing on this anywhere. I called two different parts houses and neither of them knew either.

2) Anyone have any words of wisdom they can offer? Ideas, suggestions, anything?

Thanks in advance for any assistance anyone can offer!

 

Update: I pulled the access cover and confirmed that the pump shaft is turning when the engine is cranked. I took the high pressure line completely off: A little fuel dribbles out of the pump but not anywhere near what I'd expect a high pressure pump to deliver.

I'm sorta stuck here! I can't help but believe that there's some 'trick' that only highly trained Bosch mechanics know. There is a lot of stuff on You Tube about installing a CP3 pump but surprisingly little about diagnosing issues with them.

Again I'd appreciate any assistance anyone can offer. Have any of you guys ever installed a CP3? Did you run into any of the issues I'm seeing?

 

Seems that the fuel system for Cummins engines are somewhat of a mystery. Lots of stuff on YouTube about replacing this and that, very little on diagnosis. Hopefully this post will help someone who finds themselves in a situation similar to mine!

I bought this truck new in 2004, hoping it would be more durable and last longer than a gas truck. For the most part I've been happy with it - better gas mileage than my Dodge 1500 Hemi and it is generally easier to work on. The glaring exception to this is the fuel system; obviously the weak link. I've replaced the injection pump twice, and had to buy a new set of injectors once.

Now that I'm retired and living in Louisiana mechanics are few and far between; there is only one locally and he has a six month waiting list. This means I have to fix whatever goes wrong and I'm fairly good at fixing stuff but I don't claim to be a factory trained tech. I do the best that I can. Looking back it seems that every 40-50K miles I've had to throw a couple thousand dollars at the fuel system, and I don't see that getting any better. My long term plan is to get the truck running then let it sit, using the diesel as a backup for my gas truck.

Anyway, enough whining about my truck. Since I didn't get any responses I assume nobody knows how to test a CP3 injection pump. I've had three highly trained (aka, Bosch certified) techs tell me that UNDER NO CONDITIONS should the high pressure line be removed from the CP3 pump and then the engine cranked as high pressure fuel will squirt out and possibly injure me.

That is not true. Here is a quote from the 2008 Dodge service manual under "High Pressure Fuel Pump Performance Test" (bold is mine):

4. Disconnect the Fuel Control Actuator (FCA).
5. Disconnect the high pressure fuel line from the fuel rail and route the high pressure fuel line to a graduated
cylinder.
6. Crank the engine until fuel exits this line. This will not be high pressure fuel.
7. Crank the engine for three (3) 10 seconds intervals.
NOTE: This will give you 30 total seconds of flow time. These are broken into 3 separate intervals to prevent
damage to the starter.
Fuel flow specification’s based on engine cranking speed. If you do not collect the stated amount of fuel in 30
seconds, replace the pump:
Minimum fuel pump flow at 150 rpm cranking speed is 70mL
Minimum fuel pump flow at 200 rpm cranking speed is 90mL

So there you have it, how to test a CP3 high pressure pump per Dodge. Apparently the pump does not pressurize the fuel until the common rail and all lines are filled with fuel. Who woudda thought?