IAC valve?

D Ray · #1 (**permalink**) 01-27-2008, 07:39 PM

Similar questions are mentioned on here quite a bit but here's another one with slightly different things happening....
97 expy, 4.6
I am having starting issues when it's cold outside. When I turn on the key I don't here the priming sound under the hood but I hear a single "click". Sometimes it will just die out after firing and sometimes it idles at a low rpm. Sometimes I have to hold it at about 2500 rpms for a few seconds to keep her going and then it runs fine. Sometimes it will click after firing (like something has freed up and then it will run.

Is this the IAC valve or could it be fuel pump issues?

Thanks,
D Ray

buzzard · #2 (**permalink**) 01-28-2008, 11:09 AM

Hard to tell from your description, but when my IAC valve went my truck would crank fine but just not start and/or idle when cold. It would stay running if I kept the rpm's up like you mention.

projectSHO89 · #3 (**permalink**) 01-28-2008, 11:53 AM

The "priming" sounds should be coming from the fuel tank (that's where the pump is at), not under the hood.

Crack the throttle 1/4 way and see if that helps. If so, the IAC is sticky and should be cleaned (sometimes helps) or replaced.

If not, cycle the key several times by turning to RUN for 3 seconds, then OFF. Then, hit the starter. If it fires right up, you've got a sluggish fuel pressure buildup that might be due to a restricted fuel filter or line or from a weak pump.

Steve