2002 Explorer XLT occasional not starting

[grndprx18]

I have an odd issue that is occasionally happening to my Explorer. 90% of the time it has no issues but around once a week it will not start right away. It will crank forever when the problem shows up but wont start till I put my foot on the gas pedal. When I press down on the gas pedal it shoots to 4k rpms then idles and runs fine. Any thoughs on what it could be. So far I have not been left stranded anywhere but dont want to press my luck. It has the 4.0 v6 motor 85k miles and no check engine lights. Runs great otherwise. Thanks for any help you can give.

 

[imp]

I have an odd issue that is occasionally happening to my Explorer. 90% of the time it has no issues but around once a week it will not start right away. It will crank forever when the problem shows up but wont start till I put my foot on the gas pedal. When I press down on the gas pedal it shoots to 4k rpms then idles and runs fine. Any thoughs on what it could be. So far I have not been left stranded anywhere but dont want to press my luck. It has the 4.0 v6 motor 85k miles and no check engine lights. Runs great otherwise. Thanks for any help you can give.

Assuming this occurs after the vehicle has been idle (not run) for some time, it seems likely fuel pressure, the lack of it upon starting attempt, might be a likely culprit. This might be confirmed by connecting a fuel ;pressure gauge hook-up, and seeing exactly what is going on pressure-wise after the eng. is shut off, then allowed to sit. If abnormal pressure results, replace fuel pump.

If fuel pressure testing comes up normal, (my guess) would be improperly operating Idle Speed system, be that of the solenoid-operated type, or "drive-by-wire" system, not sure which is present on your vehicle. Start Strategy for these engines involves allowing entry of MORE air into engine while cranking than needed for normal idle conditions, injecting plenty of fuel at the same time, then detecting that the engine has "caught", and immediately closing down that extra air supply. Most of the time, it works pretty well. imp

 

[swetrid]

Iac valve is bad, they tend to stick and then you have to hold foot on gas to get started.