Engine/Transmission (1994 - 1998) Friends truck is sputtering at certain RPMs

[Niro]

ok I was at my friends yesterday tabbing my KDP (which wasnt there when I took the cover off) and he was telling me about the sputtering on his truck



his truck is a 94 3500 stick with 4. xx gears



the only aftermarket on it is a green filter intake and stacks.



I think it has about 150k miles



the truck does have a 215 pump on it though



we had to replace the stocker because a fuel station filled his tank with half water and destroyed the original P7100



the truck did sputter prior to the pump as well.





it only happens around the 2000rpm range, if the truck is under boost there is no sputter

there is quite a bit of white smoke too when you rev it



anyone have any ideas where to start?



all maintenance, filters and oil are changed religiously

 

[WPeschel]

ok I was at my friends yesterday tabbing my KDP (which wasnt there when I took the cover off) and he was telling me about the sputtering on his truck



his truck is a 94 3500 stick with 4. xx gears



the only aftermarket on it is a green filter intake and stacks.



I think it has about 150k miles



the truck does have a 215 pump on it though



we had to replace the stocker because a fuel station filled his tank with half water and destroyed the original P7100



the truck did sputter prior to the pump as well.





it only happens around the 2000rpm range, if the truck is under boost there is no sputter

there is quite a bit of white smoke too when you rev it



anyone have any ideas where to start?



all maintenance, filters and oil are changed religiously

Sounds like a fueling issue to me... I would check fuel pressure at the pump???? Either filter which has already been changed, Fuel pump, or the check valve on the pump itself... Good luck. .

 

[Hammer]

Sounds like air compromising the fuel system somewhere.



One of the first places to look is the return line going from the P-Pump back to the tank as there is a small piece of rubber line,placed right under the intake shelf,which is known for going bad and sucking air.



Other places to look... .

-Pull the plug out of the fuel heater assembly and check and see if its wet,if so the heater is leaking and sucking air.

-Check the flexible braided hose which is on both the return line and feed lines located at or around the bell housing area. The lines have plastic inside them and will leak from age and cause air to get into the system.

-Also follow the lines back the frame rail,in the fuel tank area where they go into the frame at they tend to corrode and will fail causing the system to pull air also.

 

[edgeman]

This could also be a fuel filter problem... I know that I change my filter religiously and I was on my way to Ft. Mccoy Wi last year and my 97 was spitting and sputtering at 2000 rpm as well... I couldn't figure it out for the life of me but I pulled the filter and changed and filled the truck up with new fuel and the thing just started to run better... my truck also had a hard time starting and running... I would start there... then work your way through the fuel system... WhenI changed the filter... the old one had 5000 miles on it... . Could be water in the fuel also! But that is where I would start!