Engine/Transmission (1994 - 1998) Engine Runs Rough

[JoelMartin]

I'll do my best to describe this so excuse my poor description. My buddy has a 12 valve with 160 pump and at about 1,000 rpms it has a slight miss. On the fuel pump there is a banjo fitting with another bolt inside and in there is a ball with a spring. This spring can get weak and cause it to run rough at certain rpms so he got that replaced. It fixed the problem for about 1/2 a day but now it is about the same as before. It's the worst when you're slowing down in lets say 4th gear at low rpms and you get on the throttle again it kind of runs rough. I hope you know what I mean. Someone please help. Thanx in advance.

 

[Joe G.]

The overflow valve won't cause it to run rough. When mine failed my fuel pressure got down to 6PSI before I got home. It was still running smooth.



Check the injectors. Be careful because the spray can penetrate skin. Loosen each injector line. If the engine does not react to that, then the injector on that line is not working right.



If you don't find a bad injector you may have an air leak somewhere in the fuel system. Email me at -- email address removed -- for my write up on the fuel supply system, how it works and how to fix it.

 

[Missouri Mule]

Down shift to 3rd when your at low rpms in 4rth and taking off. Sounds like your lugging the engine. Which is not good for a diesel!

That is he if has 5 spd if it is an automatic it should down shift automatically

 

[JoelMartin]

The overflow valve won't cause it to run rough. When mine failed my fuel pressure got down to 6PSI before I got home. It was still running smooth.

Check the injectors. Be careful because the spray can penetrate skin. Loosen each injector line. If the engine does not react to that, then the injector on that line is not working right.

If you don't find a bad injector you may have an air leak somewhere in the fuel system. Email me at -- email address removed -- for my write up on the fuel supply system, how it works and how to fix it.

I'm not sure if it was the overflow valve he replaced but I think he said it was a spring in a return fuel line and it fixed the problem for a while. I'll tell him to check his injectors though.

 

[Missouri Mule]

The spring is part of the overflow valve. Located on the back side toward front of injector pump, fuel return line is connected to it.