I had a racetronix pump and harness installed that failed after about 5k miles so I replaced it with an aftermarket pump/bucket. It worked fine for 5-10k miles. Recently it stopped working and after an hour of the car sitting, it fired up fine and was good for about 10 more start ups.
I thought my fuel pump might be failing the next time it didn't start up. But I tried swapping relays and fuses anyway to check, no dice. Then I went to the trap door and plugged the pump to the racetronix harness that was still at the trap door, it fired up immediately. After that, I went back to using the stock harness and it fired up fine for another 5-10 times. Then the pump wouldn't prime and start again, so I go to the trap door and unplug the harness, then plug it right back in, the car starts up immediately. I've been doing the unplugging and plugging for 5 times of no starts and the car starts up immediately after I do that. One time all it took was wiggling the connector at the pump and it got it to work. Any clue what is causing this?

Short story- my fuel pump has been acting up lately and will not prime and start. When that happens, I unplug my connector at the pump(trap door) and plug it back in, and it will fire up right away. What could be causing the unplugging of the pump connector make it work?

 

"One time all it took was wiggling the connector at the pump and it got it to work. Any clue what is causing this?"

Sounds like this just may be a place to begin.............

 

Insted of randomly trying things, start with the harness & clean every connection & inspect to be sure they make good contact. Do everything outside the tank. If you still have problems, repeat inside the tank.

Random problems are hard to find, but often a poor connection. If you see a connector discolored, this is likely the spot.

 

I would say its a bad connection or a wire is about to break somewhere.