new guy to the fourms with a problem
 

i have a 1990 pu with a 5.0 and the problem is that my truck has a bad surge.when i have to stop for a short period it will idle good then it acts like runs out of gas for a split sec then the engine will pick up and the surging starts. if i put in netural before it starts it doesnt surge.i have changed the tps and checked all the vacuum lines, has anyone else had this problem or has an idea what might be wrong? also what is the average fuel mileage for these trucks, 5.0 with aod trans?

thanks, scott

Welcome to the forum. Sounds like you checked the usual for a surge, did you check the fuel flow and pressure? You will need a Haynes manual or something like that to go through the steps. Maybe a stopped up fuel filter.

Why did you change the TPS? Have you pulled codes? Throwing parts at it without knowing what is wrong is stupid and will get expensive without any good result.

here are the codes that came up when i scanned the computer 32 41 67.
the reason i changed the tps, is in the haynes manual it said that the tps may cause an irregular idle. i had bought one for my bronco so i tried it to see if that was the problem.how do check for fuel flow? the fuel pressure was in spec with the haynes manual.

thanks, scott

I'll bet that the gasket between the upper and lower intake is leaking. Get some carb cleaner and spray behind the distributor on both sides about two inches back from the distributor. If the idle picks up, you found it. Go to a local Ford dealer and get a plenum gasket for a 92 F150. These are improved so as not to break.

the gasket seemed to be fine,there wasnt any change in idleing. thanks for the help.

32 is EGR related. 41 is a lean code. 67 is a neutral switch or lever position sensor fault.

I'd start by seeing if the EGR valve is partially stuck open or is getting vacuum at idle (it should not be).

sorry to steal your post but it seems like you have a good idea already..


could a surge also come from a cylinder misfire? Trying to find out for my buddy with his 351

Man, if you are going to hijack a thread, at least jack one that has the same issue with the same engine. This guy has a V8 that's running crappy, you have a I6 with an exhaust leak.