TexasRed

I have a 1992 F-150 with the 5.8 and auto tranny. The engine was rebuilt less than 15k ago and the trans has less than 100 miles on it. About two years ago the truck started running rough, would not rev above 2k rpm and was running rich. It was not showing and codes, no check engine light. I had a local mechanic look at it and he could not figure it out. The local Ford dealership said it needed an O2 sensor, MAP sensor and a new PCM. Of course they wanted $2500 for all of this. I parked the truck and just recently decided to get her running again. I replaced the O2, MAP and PCM. It seemed to idle a little better, but still would not rev past 2k. I let the engine warm up, gave it some gas, and pieces of the catalytic converter shot out of the exhaust catching my front yard on fire. I took the truck to a muffler shop and had the dual cats cut out and a straight pipe put in place untill I can get her running right again. This made no difference in drivability. The only difference is you can smell the raw gas coming out of the exhaust and when running down the road, anything above 20 mph causes the exhaust to backfire. I pulled the plugs and they were all solid black, covered in soot. I replaced all the plugs, wires , cap and rotor and put in a new coil just for grins. Upon firing up the truck it idled perfect for about 5 minutes, I then gave it some gas and it reved perfectly, only to stick at 2k, would not idle down. I checked all the vaccum lines and did not find anything disconected. I tried to drive the truck and got 1/2 mile away and it started backfiring again and doing the same thing it was doing before, not reving above 2k. I checked the fuel pressure and get 40psi with engine off and 36psi running. I am at a loss on what could be causing this problem. Any help would be great.

ymeski56

See how long it takes for the fuel pressure to fall off after the engine is shut off. Run error code scans & clean, then test IAC as per procedures noted on this link.http://www.fordfuelinjection.com/?p=39

TexasRed

The last time I checked the fuel pressure I let it stand for 20 minutes and it did not drop at all. I was called offshore, so it will be a while until I get back, but I will try the IAC.