Just got a 92 f-150 for $350, replaced everything it needed cleaned fuel tanks replaced both fuel pumps. The truck seems to have been running worse taking a while to start loping at idle when cold. About a week ago I started the truck and unplugged the iac while it was running and it stopped
right away. Plugged it back in and tried to start it would only fire once in a while wouldnt start. Both fuel pumps work, so could the filter be plugged and not letting enough fuel get to the rail? And also what could my idle problem be? When it ran it had a hunting idle and when you revved it it would almost stall go back up almost stall again and so on until it finally smoothed out. The engine light comes on once in a while when driving and goes off until the last time I drove it it stayed on until I shut it off. Havent had a chance to try reading the codes. Thanks for any help

 

Definitely replace the fuel filter since it shouldn't be difficult. Then, you might check fuel pressure using a gauge on the Shrader valve, located on the fuel rail under the hood. Clean the IAC. Check/replace spark plugs? Check distributor timing? Not sure what else you should do from there.

 

Pull codes and check fuel pressure. Also see if it will run on ether to confirm that it's a fuel problem or ignition problem. Doesn't ever hurt to replace a fuel filter.

 

so i pulled codes 114 116 and 636 and i replaced the fuel filter and checked the fuel pressure and it was between 38-40. Didnt try to start on ether. I also put a different iac on that i know works and no difference.

 

PIP failure. Try a new distributor, plugs, wires, etc. When is the last time it had a nice tune up?

 

Havent tuned it up since I bought it due to other things like column front end fuek tank ext, I wanted to get it to run before I did a full service of the motor

 

 

I'd stick with Motorcraft parts, if you can. They are a little more expensive, but worth it. Just be aware that some of the cheaper distributors are refurbished (new plastics, new gear, etc.) but the PIP goes untouched. Make sure you get new and not rebuilt.

 

 

Have you checked the computer?

If it won't run on ether, then you have an ignition problem.