I have a '05 that seems to be having engine stumble & fuel issues. I've only noticed this since the cold weather has hit in WI. Whenever I start the truck up & my voltage is about 13vdc, I have low fuel pressure, (3-5 psi running, 1-3 before starting). I get the same low pressure & voltage after I've run at operating temps, stop & restart the truck. The fuel pressure will come up to 7-8 psi usually after the intake heater shuts off (approx 20mph) where the voltage will go to 14-15vdc & I've driven about 1 mile.

Does any one else see the same thing?

The low fuel pressure doesn't bother me as much as this occasional engine stumble that throws a P0192 (low fuel rail pressure) [that is the only code that shows up]. I can't do it all of the time, but it usually happens when the truck isn't warmed up or a very short trip & the fuel pressure is between 4-5 psi. It has only thrown the code about 5 times now. The dealer said that they will not do anything since the MIL keeps going off after X number of starts.

I originally thought that the engine stumble was caused by the low fuel pressure. But since the last time the truck stumbled & threw the P0192 that my fuel pressure wasn't coming up to the 8psi (still around 4-5psi). I changed my fuel filter. That seemed to clear the fuel pressure issue not going up to the 8psi.

I've talked with Roark at Quad about this stumble & we both are still stumped. I can't repeatively cause this stumble.

But after this last stumble I did some more investigating. One thing that I noticed I have a slight stumble at idle that is independant of voltage & fuel pressure. There is also an occasional (for lack of a term) injector pinging at idle. I can hear the my valves need to be adjusted. I also checked the oil level which has not moved. So I don't think that I have a cracked injector (but could be wrong). One thing that I have noticed is that the truck now sounds more like a Gen 2 engine than a Gen 3 since the last engine stumble with the thrown code.

I have religiously used 16oz PS during every fillup for antigel during winter & to help clean the injectors.

Sorry for the long winded post, but I figured more info I gave up front would help. I would like just to get to the bottom of this issue. Any help would be greatly appreciated.

 

If the problem is cold weather only, add a water disbursant to your fuel. The initial low pressure would lead me to believe you are having ice crystal build-up on the in-tank pump and screen.

If the problem continues when your fuel and the fuel lines are above freezing, then I would explore the possibility that the overpressure relief valve on the fuel rail has pitted and is resulting in low rail pressure.

One or more injectors will exhibit ignition rattle if the rail pressure is too low. As always, a bad injector can lower the rail pressure and create a stumble too. However, low fuel pressure at the in-feed side of the injection pump would lead me to the in-tank issue first.

 

Raise The Fuel Pressure And All The Stumble Will Go Away

 

Thanks for the info. I'm going to try the water disapant first.

I did notice that when the Quad was on level 3 at idle that the rattle went away (I normally have it set at level 2, 60hp).

Thanks again!