Troubling starting my 99 Mountaineer

[Nifty]

Hi guys,

Your board has been very helpful in past fixing various issues with my truck. In the last two weeks Ive run into a problem starting my 4.0l mountaineer. I start the truck and I can hear the pump cycle, it cranks and sounds fine. Sometimes it starts but dies almost immediately. But most of the time it cranks but won't start. The only way I'm able to get it to start when it does this is to act as if its flooded and push the accelerator all the way to the floor and then it will start. Occasionally when it starts this way I will have to hit the gas a couple of times or it will die again.

I did a little reading on here and bought a coolant temp. sensor but it has been -11 here since I bought it and I haven't had a chance to put it in. Are there any other areas that you guys think I should look at.

 

[MountaineerGreen]

It sounds like your IAC is stuck, but I am no 4.0 expert, maybe someone who knows more about them can chime in.

 

[Nifty]

It sounds like your IAC is stuck, but I am no 4.0 expert, maybe someone who knows more about them can chime in.

I'll definitely check it out. At this point Im open to suggestions. Its been a great truck I'd hate a simple problem to sour my thoughts on it.

 

[CDW6212R]

Try this, turn the key on without cranking it, and hear the pump run and shut off. Do that three times, and then crank it to start it. If it does start better, than I'd suspect the fuel supply. Regards,

 

[Nifty]

Try this, turn the key on without cranking it, and hear the pump run and shut off. Do that three times, and then crank it to start it. If it does start better, than I'd suspect the fuel supply. Regards,

I'll give that a try in a little while here. Its up to -5 outside now.

 

[Nifty]

Try this, turn the key on without cranking it, and hear the pump run and shut off. Do that three times, and then crank it to start it. If it does start better, than I'd suspect the fuel supply. Regards,

Well I went and did what you said and it started right up even at -8. So what are we looking at here then? Fuel pump, fuel filter, other?

 

[CDW6212R]

It sounds like a common symptom of an issue with fuel pressure loss, or low pressure. Does it run fine once going, or are there other symptoms?

I would suggest measuring the fuel pressure, the pump and regulator are the normal causes with fuel delivery. You need 62psi at idle, and at full throttle. My 99 truck had only 55psi when I finally got to checking it(my symptom was poor WOT performance). My pressure would drop with throttle, in park. I believe that mine was the fuel pressure regulator(which is next to the pump) or rubber hose, in the tank. I bought a used assembly and swapped it all(about $50 total).

Check the pressure, that should tell you most of what you need to know. Start shopping for a pump, FPR, or both as an assembly. They are both about $90 each new. Regards,

 

[96eb96]

Well I went and did what you said and it started right up even at -8. So what are we looking at here then? Fuel pump, fuel filter, other?

CDW is right, but first change your fuel filter if you don't remember the last time it was done. Anytime a pump is suspected that should be the first thing to do. You want a new filter with the new pump anyway.