96 Explorer 4.0L Warm Engine Hard Start

[lasteryee]

I have a 1996 Explorer XLT that has a warm engine hard start. After letting the engine cool for 15-20 minutes, I attempt to start the engine and it will start (briefly) then stalls. After stalling, the engine goes into a hard start condition (cranking the engine with a no start condition). After 5-6 starting attempts, the engine will start and everything is fine. During the hard start, I'm experiencing a little bit of backfiring. The engine has 240k with no major work (original timing chain, crank sensor, throttle position sensor, heads, etc..) I've clean the MAF, replaced the coolant temp sensor, replaced the egr sensor, and replaced the ECM. I've also cleaned the throttle body. I suspect something is wrong with the fuel pump priming cycle because the engine priming time during warm start up seem shorter (the fuel pump sound runs shorter). Could it be the fuel system? Should I replace the MAF? I've tried disconnecting the MAF during this condition and it still persists. This condition is only occurs when the engine is warm and cooled for 15-20 minutes. Any suggestion is welcomed.

 

[96eb96]

Likely this is a failed idle air control valve. I didn't see any mention of any work on it. I would replace it if its original.

The other thing to watch for is your check engine light going on when you turn the key. THis could be a failed relay to the PCM. Also, what happens when you crank? Does the CEL go out? That is how you tell if you are getting a crank signal.

The other thing could be a flaky fuel pump relay..

 

[lasteryee]

A year ago, I replaced the IAC valve. I've switch the fuel pump relay with the WOT relay. The CEL light does not go out. Also, the fuel filter has only 20k on it. Thank you for the reply.

 

[Toolbox57]

Did you get it fixed? I have the same problem.

 

[NHale623]

Did you try to see if there are any codes stored?

 

[Toolbox57]

I got 0103 on the reader that I got from Auto zone. It does not match up to the ford code book. I misplaced my little manual. It seams like after I reset the code at least three times the engine shut off. I do not know if it was a coinsidence or what. I will have to research it.
Dennis

 

[lasteryee]

I turn out to be the fuel regulator. I tested the system with a fuel gauge. The system would start off a around 25 psi and during cranking/starting, the fuel system would go as low as 15 psi (during starting problem).