Another fuel pump question on a 89gt

[minne5.0ta]

I did a search and read many post on how to trouble shoot the fuel pump but non have the issues I have. When I turn my key to run without starting it, the pump comes on and keeps on running. It'll run forever as long as the key is on. It has never shut off for me. With it running I can get 32psi on my gauge. As soon as I turn the key off, the gauge will drop to zero in about 3 seconds. When I first turn the key on, the pump will hum like I think it should, a few seconds later it will hum w/a spraying sound in the tank. It's possible it could just be the fuel being sprayed back into the tank. But what would cause my pump to run continuously and the rapid drop in pressure as soon as the key is turned off?
My drivability problems consist of hard starting and when at operating temp the car will ping badly. On hotter days it's worse. It'll pull hard through 1st and 2nd and then anything more than 1/2 throttle in 3rd is when it gets nasty. Timeing is set at 10* and everything else seems to fine. I'm thinking the pinging is caused from the fuel system. Can someone give me a run down on what tests I should perform to locate the problem?

 

[jrichker]

Fuel pressure that drops off very quickly after turning the key off is a problem with either the fuel pressure regulator or the check valve in the fuel pump. Another possibility is as you have hinted at, a leak between the fuel pump and the tubing that connects it to the outside world.

The pressure checks will require a 0-60 or 0-100 PSI gauge (Home Depot or Lowes), some adapter fittings, and some fuel proof hose. You need some fuel line disconnects to separate the fuel lines up near the alternator. You get to separate the fuel pressure line (it has a schrader valve on it) and connect the fuel proof hose to it. The gauge mounts on the other end of the hose. Tighten all the connections, doing your best to make sure everything is leak proof. Fire is a nasty depilatory, and you need all the hair (and eyebrows) that you have. Turn the ignition switch on, but do not crank the car. To trick the fuel pump into running, find the ECC test connector and jump the connector in the Upper RH corner to ground.

Watch the pressure build up and be prepared to cut it off quickly. There is no pressure relief, so it can get up past 100 PSI very quickly. When you remove the jumper, the pump should quit running. If the pump check valve is bad, the pressure will drop very quickly. If it does, the pump is bad.

If the pump holds pressure or bleeds off very slowly, the fuel pressure regulator is bad.

 

[superhuaman]

your pump should not keep running when you dont start your car. it sounds like either someone hot-wired it, or the FP relay is stuck closed.