I have a 2003 Dodge 3500 that I purchased new. From the start I have had issues with it stumbling on throttle tip in. Have taken to dealer until warrantee was out. It has gotten progressively worse to the point it will sometimes die when let up on throttle. Have taken to many shops and could not fix. Only code ever shown was a cam sensor (replaced) and now a code indicating key is not programmed to CPU. Having my own shop I am now working on it. Other things changed is the addition of Air Dog fuel pump & filter system, fuel rail pressure gauge. I even removed the CPU and sent off to see if it needed reflashed, it did not. The fuel rail pressure will make wide sweeps from less than 5000 to over 25000 while you hold the throttle steady. Pulled the banjo nut off the rail pressure relief valve, not leaking, but fuel is bypassing the fuel pressure limiting valve on the pump, is this normal? Any other idea?

 

Have you replaced the FCA (Fuel Control Actuator)? I would start there.

 

x2 on the FCA.

 

Have not changed the FCA, did not know if it would cause problem due to the fact that it shows pressure swing with throttle held steady. Is there a way to check with out throwing $ at it? Thanks

 

Almost certain its the FCA man. Part is way cheaper through Cummins dealer.

 

Thanks sounds like a good try, will find a FCA and see what happens

 

Best way to test is to unplug and run motor. If motor runs just as troublesome, than faulty FCA.

 

Good idea will try tomorrow if get in shop. Thanks

 

OK back to shop. I decided to check Injector pump out put before unplugging the FCA, thinking that if I unplugged the FCA and still had problems I would not know if it was the FCA or pump. The Injector Pump did 150 ML in 30 sec. over the minimum of 70ML so assuming the pump good unplugged the FCA. When started the fuel rail pressure shot up to 30,000+ PSI!! shut down and plugged back in and rail pressure back down to 5000 to 7000 PSI at idle. At wits end so will pop for a new FCA and see where we go from there. Thanks.

 

With what you just stated.....your FCA is good.

Sent from my high tech squawk box

 

Thanks Justin I agree thinking if FCA was bad it should not let rail pressure to go to. 30K. I seem to be in the throwing $ at it stage so hav FCA and pig tail coming anyway. I am still ? The rail pressure relief valve, being mechanical could have weak spring or? Am checking on price and availability. If that does not do it might consider a new engine wiring harness.

 

Have you removed the banjo bolt from the relief valve to see if it had fuel sitting in it? From what I understand, it loses its strength once it pops. You could be losing a lot of RP because of that.

Sent from my high tech squawk box

 

Yes did remove banjo bolt no fuel bypass at idle. Did not rev up due to the fact the relief valve and FCA on same return line and FCA letting fuel by and making mess.

 

FYI. I did get back in shop this weekend and changed out the FCA and pigtail. So far So good! Fuel rail pressure is holding steady at all RPMs and loads. Also the stumble at tip in of throttle is gone the fuel pressure responds quickly and does not fall off at throttle tip in. I will use the truck tomorrow to pull a loaded trailer to a job site with a very rough road. This should show if we got it. Thanks for all the help and interest.