i have a 2001 f-150 lariat triton v-8 5.4 l.......the truck starts but barely stays running w/ foot on the gas.as soon as I let off the gas it dies completely. the radio,dash,lights etc.....everything comes on. there is no check engine light on or anything like that. my husband replaced the fuel filter lastnight but it did'nt help. any ideas would be appreciated. my husband and i know nothing about mechanics but we do have a repair manual. if you could try to respond in lamens terms it would be greatly appreciated.

 

several things need to be checked for a real diagnosis, best bet is to read the TROUBLESHOOTING GUIDE in your repair manual . This will at least narrow down the terms of the very general complaint

 

When you turn the key to RUN but don't crank the engine does the fuel pump run? Sounds like the relay mighta gone bad.

 

ummm, how do i see or hear if the fuel pump is running ?? where is it located ? thanks so much.

 

when you turn the key on... leave the door open.. you should hear a high pitch whine down under the cab/bed.. thats the fuel pump applying pressure to the system.

 

yes when i turn the key i do hear a noise coming from under the bed.

 

could it be the fuel cut off switch ? it has'nt been in an accident or anything.

 

This sounds like the IAC (Idle Air Control). Very easy to change.

 

I agree. What you described is the exact symptom my truck experienced. A new IAC fixed mine. In my case, I had to feather the gas pedal to keep it running. Once I got going and the truck warmed, it idled fine on its own.

Changing the IAC is a very easy fix for a DIY'er. I think I paid around $50 for the part.

 

Replace the IAC valve.

Reset the computer (remove the 5A PCM fuse or disconnect the battery, either for the duration of the parts replacement).

Steve

 

I betcha it's your MAP sensor.

On Tuesday, my friends '98 Dodge did exactly what you described. Wont start without foot on gas, and will barely run when on the throttle. Unplugged the MAP sensor and she starts and runs just like normal

 

well my truck starts right up and sounds great but i have to put my foot on the gas to keep it running. it absolutely will not idle on its own and can't drive it.do you know if autozone has the diagnostic machine to be able to tell what is wrong and will it even show up ? do i need special tool to look at iac valve and map ? geez i just bought this truck not even a month ago and its christmas time.sucks.not much money.anyway thanks guys!!!!!!!

 

The IAC is a VERY common item to fail, especially if you are in a colder climate.The symptoms you describe are classic for the IAC sticking, failing. Check Direct Ford Parts for the OEM part. I believe the IAC runs around $75 and is easy to install or your dealer will replace it for around $200-$250.

Link to Direct Ford Parts

http://www.trademotion.com/partlocat...?siteid=214290

 

my hubbie went to autozone and the guy said if it was the iac that the check engine light would be on......its not and no one on here has mentioned it so whats up ? thats not true is it ?? anyway my hubbie went to get some tools to get to the valve so we can look at it.

 

I coppied this from frequently asked questions by Racerguy:

Q: My truck idles roughly or stalls at idle. What could be the problem?

A: A fairly common idle related malfunction in these trucks seems to be the Idle Air Control valve motor. This valve sits on top of the throttle body and holds the butterfly valve open at idle so the engine can breathe. A sluggish or malfunctioning IAC will prevent a constant idle. The problem sometimes only presents its self when the engine in cold. This certainly isn’t the only thing that can cause a rough idle, but If you find yourself having to keep pressure on the gas pedal to keep the engine running, this may be a place to start. Typically, just cleaning doesn’t offer any improvement, if the IAC is faulty, it usually needs to be replaced.
For some pictures of the IAC take a look at Fordman311's gallery at https://www.ford-trucks.com/user_gal...7&albumid=14860