Engine/Transmission (1994 - 1998) Sputters at lower rpm's

[KMott]

Ive been complaining about low power for quite a while now, and im still not convinced my truck is running right. (i moved 2 yards of dirt today for someone, and the truck barely accellerated up hills in town) I ordered a set of ISSpro gauges, so that will give me a better idea on how the boost/ fuel is working.



It was brought to my attention from another cummins owner that when my truck takes off it almost sputters, like it is missing or something. What could cause this?

 

[Signal73]

Do you have any modifications done to it? Maybe you can fill out your signature with some info so we can see what you are running to help you better.

 

[KMott]

Sorry, i filled out my truck profile last time, and thought it would show up on the post. Just making sure that it works now.

 

[JAmos]

You might start with changing fuel and air filters. The fuel pre heater screen can get clogged too. The rubber fuel lines can rot internally and choke the fuel supply off. The timing might need to be adjusted. There probably is a screen on the fuel pickup in the tank that could get plugged. Does the truck make any smoke? If so what color is it? The waste gate can get stuck open sometimes. Hope this helps.



Jordan

 

[KMott]

I've actually covered all of those except the in-tank filter, which i did today since the tank was almost empty. It wasnt clogged at all. I also checked the line vacuum between the pre-filter and transfer pump today and it held 5hg unless it revved it up it went a little higher. So that should suggest no restrictions or airleaks. Fuel pressure is 30-40 psi under load when going down the road. Ive pretty well eliminated anything in the fuel supply side, and now im looking at injection or turbo. This truck has a tampered odometer so it could have 400-500,000 km's on it. This is why im thinking injection system may be getting weak. The wastegate actuator and afc diaphragm were just replaced. I guess once i get gauges i can make sure the turbo boost is where it should be. If its low i can understand how it would cause lots of problems, because having low boost will also result in the afc not working properly, and thus making it also a fuel problem. The truck smokes white a little when its cold, but goes away once it warms up. It never smokes black under and conditions.

 

[Matthug]

All 94's had the WH1C turbo, mine did and I was only getting 8 PSI boost out it. I think the wastegate diaphrams were weak on the WH1C's or something. I swapped mine out for an HX35 and I had faster spoolup and more boost about 16-18 PSI.

You also have the smallest injection pump, the 160. The timing could probably used bumped to 16, that will help a lot. Get some kind fuel plate in there too after the gauges, it really wakes the truck up. Then get a 3000 RPM governer spring kit.