Hey guys, I,ve read alot of helpful post but have never posted on any forum or blog or anything. But.... I need some help. I have a 1992 Chevy truck 2WD, 5.0 TBI that I bought new and have taken good care of. It now has 298,000 miles on it. It started running rough after it warmed up. When I would give it the gas it would spit and sputter and backfire. Remember... this is after it warmed up. It runs great before it warms up. Anyway, I decided to get a kit a rebuild the throttle body. I found it clogged, dirty and the fuel pressure spring was broken. I got it all put back together and was proud to get it fixed. But ... same thing. It ran great until it warmed up. Pulled code 32. R+R the EGR. I got it all put back together and was proud to get it fixed. But ...same thing. It ran great until it warmed up. Pulled code 15. R+R coolant temp. sensor. But ... same thing. Now it won't put off a code. I checked the TPS with a multi meter. I looked at the distributer and all around for vac leaks but don't know how to test for leaks. Fuel pump comes on when the key is turned on but I don't have a pressure guage. The exhaust looks fine but I did notice a intermitting skip in the sound of the engine through the exhaust but you can't hear it by just listening to the engine run. It still idles fine (most of the time) after it warms up but you have to be real gentle on the throttle to rev it up or it will spit and backfire and go dead. Then it's hard to start without letting it sit for a while. If it would give me another code I'd know what to do. Thanks for reading. I don't really know how this forum thing works but I hope somebody will send me some ideas that I can read. Thanks again, Eric W.

 

Seems like you already replaced your EGR, try unplugging the vacuum source to the EGR valve and plugging the line and see how it does. Almost sounds like the EGR is being pulled open and then is going too far - like the EGR vacuum solenoid is causing an issue.

Just a thought. You said you checked the distributor, but what do you mean you checked it? Did you physically pull the distributor to check for the bushings to be sloppy, or did you pop the cap off and wiggle it from the top?

 

I had an issue with a '95 Sierra that would idle but sputter and die upon gassing, unless you lightly pumped the gas peddle, but even then...

Turned out to be a faulty fuel pump. Apparently sometimes they can go without fully dying. Rented a pressure test kit from the local autoparts store to test and confirm. Might be something to look into.

 

The distributer cap , pickup, wires and plugs are all less than a year old. I just took the cap off and looked for cracks or moisture and loose connections. It only spits and sputters when you give throttle. If you keep it at the same RPM it runs fine. I think I'll put a new fuel pump in it and see what happens.

 

My old 89 pickup was like that too. Pump was "dead" at 8 psi output, but couldn't support enough fuel pressure to give it any throttle. Worth a shot I guess if you're willing to give it a shot.

 

I put a new fuel pump in it. Same thing. It ran great until it warmed up. I got about 8 mile down the road and started up a hill and it started spitting and backfiring. That's what has me so puzzled. I thought I had it fixed until it warmed up.

 

Did you unplug the vacuum solenoid to your EGR valve yet? If you're egr valve is being opened when then engine doesn't need it, then that can cause the same issues.

Personally I'd want to get a scanner on it and watch the 02 sensor as well. Sounds like it's missfiring too.

 

Distributor Control Module? IDK just through'n ideas out there