theville89

my truck would not start today at work when i was leaving. its a 00' lariat 2wd 5.4L, i turned the key and it tried to start but wouldn't so i done it again but i gave it some gas and it started, but would drop down below 500 rpms if i took my foot off the gas and it tried to stay running but would end up shutting off. i had to keep my foot on it while running to keep it from dieing. its done this twice before just this month and never before. the other times were not as bad. my grandpa said it was probably the fuel pump going out. and by the way i drove it home and once i got there i put it in park and it stayed running. i shut it off and restarted and it stayed running. so whats going on. battery is good, plenty of gas, and no check engine light has come on.

any help would be greatly apperciated!!!!!!!!!!!!

Good old Bill

In theory the IAC (idle air control) maintains idle speed, and fast idle speed (cold engine). The TPS (throttle position sensor) tells the PCM (powertrain control module) what position the throttle is at, due to the mechanical linkage to your foot. Here lies the challenge, whats wrong, no codes doesn't help. I ask you, what else was happening? Something else is probably happening. Was the engine turning over very slow when engaging the starter or was it cranking at a normal speed? Did all other electrical devices work properly. I'm not the most skilled here, common sense says, something else is going on.

Just call me Sean

iTrader: (1)

Check for codes. It is possible the check engine light came on and went off without you noticing it. You said the light isn't on, but you didn't say you checked for codes.

theville89

i talked to a mechanic earlier today and he said they can run a dianostic check on it but he said that will not guarantee any thing . he said they it would help better if it was happening while at the shop. but the thing is after i drove it less than a mile home from work and after sitting for a few hours it started and ran fine. my grandpa followed me to the shop and he said when i pulled out of the drive way after sitting for a while quite a bit of water came out the exhaust. the guy at the shop said i could have gotten some bad gas and it sounded like i had some water in the tank and he said use some heet water remover to put in the tank and see if that helps. by the way i called a few places to see what they charge for a fuel pump install just in case i might need that and these are what i found.......Pepboys $428, Ken Towerys $520 (includes fuel filter), and (Ford $750 ) when i called ford they said $380 so i was like wow ok, but then he said thats not including the fuel pump, with the pump its a total of 750. so you mean a fuel pump is $370 bucks...i dont think so buddy i like ford products but there service prices are a joke. they are crazy. they wanted $450+ from me one time to install door lock actuator valves.

dewman

www.rockauto.com for the fuel pump. I had a 93 Dakota that the fuel pump died on. I got a Bosch fuel pump way cheaper than anything local, and that was including the shipping. I save about $125 buying the pump and having the shop install it.

That is, if you actually need a fuel pump.

theville89

thats alot cheaper! but then again until i figure out what it is im going to wait and see what the heet does. thanks though!

theville89

i was talking to my girlfriend a few mins ago and her moms boyfriend is a master tech at ken towerys here in louisville and he said that it sounds like i have a vacuum leak or my idle air control motor or something like that was going out. have any of yall heard of this type of thing. he also said f150s are bad about having some pvc pipe getting cracked and causing air leaks.

would apperciate any help.

CriSSes

Hey theville89,
Did you ever figure out how to solve your problem? I have a 99 with the 5.4 and it is doing the exact same thing you described. Yours is the only post I could find by searching that matched my problem.

Thanks!

theville89

well i talked to my gf's step dad who works at ken towerys and he said it was either a vaccum leak or the IAC valve. so i removed the IAC valve from the back of the intake and went out and bought a new one for 70 bucks at napa. i would have replaced it with another motorcraft but the shops here were closed at the time. all i can say is that was like a month or so ago and i havent had a problem. good luck !!!!!!!