Crazy cold start problem
 

I'm new to the explorer, and fuel injection for that matter. I just got a 1992 with 4.0L auto. The problem it had when I got it was this: Go to start it and it turns over fine, but no signs of ignition. In order to get it started you had to cycle the key probably 30 times (prime the pump) to get it to fire a few times but wouldn't stay running (just a couple kicks). Then do this a second or third time and it will start and run like new. It idles perfect right away, and drives great on the road even if you hit the gas hard etc. You can shut it down and start it up again no problem. But after it sits and gets cold it won't start. So I replaced the fuel pump and sending unit thinking it was the check valve. Now it only needs the pump primed maybe 10 times and it starts. but the problem is still the same. I don't think regulator or fuel filter or injectors because it runs so perfect. I tried to find fuel leaks but can't locate any at all. Some sort of cold start sensor or something? oh and hitting the gas while starting doesn't seem to help.

Any ideas would be great thanks.

i have the exact same problem with a 2001 explorer sport. i am about to change the fuel pump but im not sure this will fix it. def. a cold start issue.never happens in the summer.it has gotten worse.someone said something about a air leak above the head gasket but that would probly effect it driving. it drives great once started.BOGGLED

I think that both of the engines probably have the same thing wrong with them. if I had one I would have the maf sensor cleaned and checked if that still didn't solve the issue then have the tps checked and or replaced.

No expert here but, sounds to me like an air bubble at the injector head ... hear me out and see if it makes any sense ... if either or both of these gas ever been ran out of gas and the injector rails,etc were never properly bled, there is possibly an air pocket at the high point, causing the pump to cut out at its max pressure but, only feeding air to the engine.
Like I said, I am no expert but, this makes sense to me.

If you turn the key on and off slowly a few times, does it start any quicker when cold?
The fuel pressure regulator can leak internally and allow the fuel to go back via the return line.
Can you get your hands on a fuel pressure gauge that you can leave connected overnight and see what pressure you have in the AM ?

you know, it's really easy to diag what's going on here with the use of just about any cheap fuel pressure gauge. With key on, eng. off, the presure should reach at least 30psi and hold for at least 2 minuets. If not, further diag is necessary.
However, this generation explorer also had ledgendary problems with the crankshaft position sensor.