Trying diagnose a stall problem and finally discovered the problem....

I installed a brand new fuel pump early last year.

For some reason the pump is turning off and on when it shouldn't be.... thus stalling the car.

If I take the fuel pump relay out, short the connections with a jumper wire, the fuel pump will run for something like 30 seconds to 1-2 minutes (sometimes many minutes), stop for about a minute, then start back up. This is without the key even in the ignition.

So the computer isn't doing it (relay bypassed)... does the pump have any sort of internal shutoff if pressure is too high etc....? or is this pump now also bad? :-(

Would a bad fuel pressure regulator cause this condition?

 

gut feeling is thermal cut out, maybe a bad fuel filter or blocked teabag in the tank is causing the pump to cut??

 

Hmmm.... interesting thought. Perhaps this is why I didn't have a problem in the winter (cold fuel).

I didn't know they had a thermal limiter in it.

I did change the teabag out, cleaned the bottom of the gas tank and replaced the fuel filter when I replaced the pump.... basically I did about everything I could think of to NEVER have to replace that pump again :-)

 

I looked at the fuel lines near the tank to see if they were kinked or something... and they look good.

Also having a problem with the thermal theory. Basically if I just jumper the relay pins, with the car off, the pump runs.... and it runs for a while (sometime several minutes) then shuts off....then starts back up.... and runs for many more minutes....then shuts off. It is random, with no pattern I discern.

e.g. the car had been sitting all night, never ran.... I went to pull it into the garage (takes about 30 seconds) and the pump stopped/car stalled. Once in my garage, the pump ran for many minutes before stopping....restarting.

I guess I am going to try and replace the fuel filter and directly wire the fuel pump to the battery to see if that helps... after that, I guess I am going to have to replace the pump again :-( .... this time I think I would use the cut a hole in the rear window deck technique.

 

Replaced the fuel filter.... no change.. the pump will run for 10 minutes or so... then just cut out for a few seconds, enough for the engine to stall, then keep running.

Guessing this brand new pump with less than 5K miles on it is bad... I can hardly believe it.