ok i have done some reading on people with similar problems on here but nothing seems to be leading me down the right path so heres my issue. its a 87 f150 with the 4.9 efi the truck was running sluggish and rough and after it was parked it wouldnt stay running, you can get it started and feather the gas to keep it running for a short time but it will die as soon as you let off, i have tried swapping over the iac valve from a buddies truck but that did nothing. it has new fuel filters and i can hear the fuel pumps turning on, where should i go with this i am thinking about checking the tps and fuel regulator but im not sure i couldnt get the scan tool from my work on it ps i work for a ford dealership but i work on diesels so im no expert on gas drive and the trucks older than me hehe any help or maybe if you could steer me in the right direction that would be great just let me know if you need any more info.

 

Ah, could be any of many things. Suggest the first bet would be to pull codes - but not sure if you have the EEC-IV or the DuraSpark setup.

 

alrighty ill grab the wgs or whatever its called from work and pull codes last time i tried though i couldnt get it to work not sure if somebody at work broke the tester and just put it back or if the cig lighter is shot.

 

Hang in there bud, help is on the way, unfortunately, it ain't me. Question, you have access to a tester that plugs into the cigarette lighter? That is cool, have never seen or heard of that. Lets talk basics for a brief second, the IAC controls idle speed (been swapped), the TPS tells the computor of throttle position, the CPS informs of crankshaft position. Lets forget about the most commonly changed item (has no bearing at idle) the infamous 02 sensor. (Would love to have stock in that company). Vacuum leaks will effect idle but not higher RPM. A MAP sensor reads all load ranges. Boils down to need to read some codes for malfunctions.

 

I have a 91 4.9 and our trucks are pretty much laid out the same. You can check your codes with just a short jumper wire or even a large paper clip and watch your check engine light flash the codes. Just call me sean posted the how to here on the forum.

https://www.f150forum.com/f10/how-retrieve-trouble-codes-obdi-10907/

If you pull the codes and post them, we will be alittle more help. Ill do alittle more research and get back to you.

 

I actually dont restart my truck with the jumper wire connected for the test. I just turn my key to the run position and it displays.
In the picture that sean has taken, you dont need the white wire at all if you plan on using the check engine light flashes. Keep in mind that the codes will repeat themselves twice. May be two digit codes but mine flash three digit codes. 1-1-1 means things are checking out fine; this will also repeat itself but the codes to really watch for follows these.

IMPORTANT:
If you disconnect the jumper wire before the test completes, it will erase all the codes in memory and you will have to redrive your truck so the computer can relearn them, so let it run its full course first.

I keep a jumper wire on my sun visor so I can check mine at anytime lol.

 

Amen to that! Pull the codes FIRST, test Second, throw money at it Last. Or you can go in any order you want. Could be the TPS and you can test that for function.