Fuel pump cycles when it wants. Runs great once running though

[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?

 

[2000StreetRod]

Fuel filter replacement?

How often have you replaced the fuel filter? If the answer is not every 30,000 miles then your fuel pump is probably just tired from pumping thru a clogged filter. You can swap the fuel pump relay with the horn relay next to it but you have already replaced the relay once. The fuel pump relay is not energized unless the PCM relay is energized. If "CHECK ENGINE" is illuminated when the ignition switch is On then the PCM relay is energized. You can check the electrical connections at the pump to make sure they're tight.

 

[1taylor2few]

Ive only owned it for a couple months now so Im not sure if the fuel filter has been changed. It just doesnt make sense to me that the pump would only fail during startup. Once it starts in never dies or misses. If the connections were loose I would think it would fail even while its running. Ill try switching the relay with the horn relay. Who knows, maybe I got a bad relay from the parts store? I dont know. Thanks!