just got 1992 4x4 cummins today it starts fine and idles good but once u go part throttle it misses and you let off and it lets the smoke roll, and goes to idleing just fine. any help would be great. thanks

 

Could be a bad injector. One at a time and while idling, loosen each one of the high pressure lines at the injectors (17mm wrench). Listen for a change in sound while idling. When the sound doesn't change, you found your bad one.

 

Thank you Jim i'll try that today or tomorrow when ever I get the time.

 

It might be a loose spade connector to the fuel shutoff solenoid (FSS) causing it to lose power momentarily and shut off fuel.

 

I had a spade connector come off the fuel solonoid when the skinny was depressed to hard and then it would touch again when i let off. threw me for a loop..till I found the problem

 

Yep I was having the same problem. The throttle assembly was interfering with the wire at certain throttle positions. This might not be Jmadison's problem, but I figure I would mention it.

 

change fuel filter

 

Thank you I will be checking all of these tomorrow

 

I have tried loosing the high pressure line and all of them change the idle sound I will get a fuel filter and change it to see if it changes any thing also. The fss conecter looked good. any more ideas would be great. could the lift pump not be giving enough fuel? idk what it is I think it is getting enough fuel because once you let off the throttle smoke. The smoke is bluish gray.

 

when i first got my truck and started turning it up it would smoke under throttle but it would come out in puffs and when i let off it would let out some more smoke but then i changed my fuel filter and it didn't do that anymore. Could be something else though. Are you sure its bluish grey smoke? or does it just look that color in the sunlight?

Mine also used to pop at higher rpms when revved up in park or neutral. Since I've gotten newer injectors and bumped the timing it doesn't do that anymore. If you have over 200,000 on your injectors I would suggest looking for a new set or gettin your stock ones cleaned and pop tested.

 

It may just look like it in the sunlight. I am going to be it town tomorow so I am going to get a fuel filter. Also how can you tell if a fss is bad or how to test it to see?

 

The truck is just under 200,000 miles how much does that cost usually

 

some shops will pop test your injectors for free I've heard but not sure how much to reset them. My local shop wanted $100 to $150 just to pop test them! You can buy a pop tester on ebay for that price! or I just bought a new set of POD injectors for about $325.

 

got it running the injector pump was gummed up in side ran strait injector cleaner for a little bit and it started to get better finally she let loose and was able to go 80 mph