99 explorer fuel pump cylces intermittently with key

[1taylor2few]

I have a 99 explorer and for the longest time I would go to start it and it wouldnt start. I'd let it sit for a few seconds and try it again and again until it finally started. I realized that the pump wasnt cycling with the key during the times that it wouldnt start. So after that, I would just cycle the key on and off until I heard the pump cycle and then it would start right up. Once running it never missed, stalled or triggered a check engine light. So it seems like the pump is working fine. I replaced the bigger of the two fuel pump relays (i was told that is the one that is related to startup) and nothing changed. Now, however, the fuel pump just wont cycle at all. It seems like a relay problem to me. I just have a hard time believing that its a fuel pump when once it ran it ran great every time. Any ideas on what the problem could be?

 

[bdmaash]

ok then, change the relays since fuel pumps don't fail.


was that what you needed to hear?

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I replaced my fuel pump just because I had some intermittent issues, no problems since
Oh, check the parts before you randomly start spending money, if you think it's a relay - you should be able to bypass it, and if you don't know how take it in to someone who does.

 

[2000StreetRod]

tired pump

How often has the fuel filter been changed? If it hasn't been changed every 30,000 miles your pump may just be tired from pumping thru a clogged filter. You can swap the fuel pump relay with the horn relay next to it if you still think its bad after having replaced it already once. The fuel pump relay is not energized unless the PCM relay is energized. Does "CHECK ENGINE" illuminate when the ignition switch is in ON. If not, then you don't have power to the PCM. You can also check the electrical connections at the pump to make sure they are tight. Fuel pumps frequently fail at turn on rather than while running. That's a good thing so you don't drive somewhere with a weak pump and then get stranded along the way.

 

[1taylor2few]

well im not saying fuel pumps dont fail but if its bad its bad, if its intermittent its intermittent. It wouldnt ONLY be intermittent until the engine starts would it? I guess thats what Im trying to figure out. Ive never got a check engine light and its never stalled while driving. Thats the only thing that makes me think its NOT the fuel pump. I guess I was hoping someone would reply saying oh its the _______ and heres what ya gotta do to fix it. Maybe a relay i didnt know about or a reset of some sort.......or maybe the ignition? or the ECU? I have no idea. I would just rather not drop the tank and put a fuel pump in it if I dont need to. Im sure thats what Ill end up doin though............

 

[explorerguy89]

definately sounds like a voltage prob cause a clogged filter wouldnt cause it to not work so yea check wiring and relays

 

[2000StreetRod]

???

How often has the fuel filter been changed? If it hasn't been changed every 30,000 miles your pump may just be tired from pumping thru a clogged filter.

???

See Why change fuel filter?

You can swap the fuel pump relay with the horn relay next to it if you still think its bad after having replaced it already once.

???

The fuel pump relay is not energized unless the PCM relay is energized. Does "CHECK ENGINE" illuminate when the ignition switch is in ON. If not, then you don't have power to the PCM.

???

You can also check the electrical connections at the pump to make sure they are tight.

The above can assist you in determining if the fuel pump is actually faulty. You can also perform the Fuel pressure test procedure