4.9 hard starting when warm
 

hi i have a 94 f150 4.9 5spd and it starts fine when cold but if i drive for awhile and it gets up to operating temperature and i shut it off it takes a lot of cranking to get it to start... any ideas what this might be?

When it does start, does it lope or idle rough? Does it do this all the time? Is the "check engine" light on? If it does start hard next time try tapping on the IAC (idle air control) valve, see if that helps. The IAC may be going bad.
John

it will sputter for awhile until i tap the gas a bit and then it idles fine and no the check engine light is not on

My 96 F150 with the 300 I6 did the same thing when warm or in hotter weather... never in the cold, it turned out to be the IAC. I replaced it and haven't had a problem since.
John

hmm ill hafta try tapping on the iac then

You could try that, and if that doesn't work... try taking it off and cleaning it. It's most likely carboned up inside causing the valve to stick, I'd try using carb cleaner or better yet Sea Foam.

Ok I will do that tonight then

Well I used MAF cleaner on it and WOW did it make a difference the a/c doesn't effect the engine as much and it starts beautifully when warm :D . Thank you so much for the tips it is greatly appreciated.

I am having the same problem with my 96 4.9. Where is the IAC? I don't have a shop book yet. Is this part expensive? Thanks in advance!

Idk about price but it's right on top of the intake and looks like a cylinder with wires coming out towards the drive side.. That's on my 94 I'd assume it the same for your 96 but not positive it has 2 bolts one on each side. 1/4 if I remember right

I thought that was it. Thanks for the quick reply! I am going to give it a shot this weekend and see if it cures the problem.

The only thing is if your going to clean it idk how it would react to carb cleaner I thought I'd be safe and went with MAF cleaner because I didn't kno how sensitive it is.

I will go with the MAF cleaner then. Thanks again

Not a problem glad I could be of help

I know this thread is old but I came across it searching because my 1992 F150 4.9 E4OD has been doing the same thing for awhile. So yesterday I went and bought a new IAC and put it in now since its winter I wont find out until the warmer weather. But now when I put the truck in drive it idles up more than it used to and then idles back down. The old IAC defiantly had carbon in it the inside of it was total black. I rechecked everything gasket is seated right I don't believe theirs any leaks. No CEL is on either. It has gotten alittle better but it still does it. Does it take so many start cycles for the computer to re learn the new IAC? Thanks