Stumble and loss of rail pressure

[hunterdiesel]

After leaving the truck to idle for 15 minutes or longer it will stumble upon take off. The rail pressure is dropping to around 1,000 psi then recovers and takes right off. It is only a short stumble for a few seconds then completely clears up. Within a few miles the problem completely goes away. I am thinking a fuel supply problem but need help figuring it out. Truck has 105,000 miles.

 

[cerberusiam]

If it was fuel supply it would probably do it all the time. My guess would be FCA and\or COV on the CP3.



Wow! Thats too many acronyms in one sentence. :-laf



FCA is the fuel control acutator that actually controls rail pressure. They get sticky or worn and don't work consistently. COV is cascade overflow valve that keeps the case pressure up so the COV will work correctly. They can also not work correctly and cause fluctuations in pressure. They are both on the IP so easy to change out and test.



Putting a gauge on the CP3 inlet should tell you if its fuel, might be the easiest and cheapest route instead of just throwing parts at it.

 

[Elite1]

If it was fuel supply it would probably do it all the time. My guess would be FCA and\or COV on the CP3.



Wow! Thats too many acronyms in one sentence. :-laf



FCA is the fuel control acutator that actually controls rail pressure. They get sticky or worn and don't work consistently. COV is cascade overflow valve that keeps the case pressure up so the COV will work correctly. They can also not work correctly and cause fluctuations in pressure. They are both on the IP so easy to change out and test.



Putting a gauge on the CP3 inlet should tell you if its fuel, might be the easiest and cheapest route instead of just throwing parts at it.

IP??? acronyms...

 

[TCDiesel]

IP. Injection Pump GT

 

[Elite1]

IP. Injection Pump GT

Thanks... after I posted the question, I found a page listing acronyms. It said, IP= Instrument Panel ... which made it even more confusing!

 

[hunterdiesel]

Fuell pressure is great

Put a gauge on the IP inlet and found that I had 5 psi of fuel pressure while the stumble was occuring. I will check the FCA next, then the COV. Thanks to everyone for the help will let you know the results.

 

[p-Bar]

what year truck do you have ? You need to fill in your sig. Sig= signiture

 

[Elite1]

If it was fuel supply it would probably do it all the time. My guess would be FCA and\or COV on the CP3.



Wow! Thats too many acronyms in one sentence. :-laf



FCA is the fuel control acutator that actually controls rail pressure. They get sticky or worn and don't work consistently. COV is cascade overflow valve that keeps the case pressure up so the COV will work correctly. They can also not work correctly and cause fluctuations in pressure. They are both on the IP so easy to change out and test.



Putting a gauge on the CP3 inlet should tell you if its fuel, might be the easiest and cheapest route instead of just throwing parts at it.

I have a similar issue, but only occurs at idle and is now occuring more & more often. The truck stumbles and almost dies, than idles fine for another minute or so, then stumbles again.



How much money approximately are the above parts (FCA & COV)???

 

[TCDiesel]

We have test senors ,But they are out to the end of the Week. .

 

[cerberusiam]

Parts here:



Dodge-Dodge Cummins Diesel Truck Accessories – Geno’s Garage





and here







Common Rail

 

[BMeier]

I had the exact same problem happen on my '03. It would stumble and the rail pressure would drop off and come back. I hooked a fuel pressure gauge on and when it would stumble the pressure never changed from 8 psi. I swapped out the FCA with my buddies pickup and the problem still occured. The lift pump momentarilly stops causing a stop in fuel flow which will make the engine stumble, my factory lift pump was failing. I replaced it with the factory pump from genos and the problem went away, a year and a half later the replacement failed with the same stumbling problem was back. Now I am running a FASS direct replacement pump which runs 18 psi and have had no problems.