fuel pump keeps running

[Dave]

Hey all..

I've got a 91 Beretta GT 3.1, Auto, Air, Tilt, Cruise, power everything.. (not sure what all info you need 'bout this problem) but this is something I can't seem to figure out at all...

every time I shut the car off, the fuel pump keeps running, so far for the longest I've noticed of almost 10 minutes, so now I pull the fuse when I get out of the car, but rather then just doing this quick fix, I'd like some ideas as to what the actual problem may be.. any help would be awesome...

--Thanks
-- Dave

[Anonymous]

Something with the ignition possibly?
Try unpluging your battery to reset the ECM.. never maybe its acting weird worth a shot.

[Dave]

Tried that one, didn't work (blah!)

I'm ready to put in my own relay, and manual switch to control the pump.

[bszopi]

You might just need to swap the fuelpump relay. If you have a multimeter, next time you turn off the car, check to see if the relay is sticking. If its not getting a "TURN ON" signal, but the relay is still shut, then its a bad relay. If it is getting a "TURN ON" signal, then you'd have to trace the problem further back (which would lead most likely to the ECM, but without looking at the schematics, I can't be 100%).

[RLJ]

Could it be a bad or leaking fuel pressure reguator on the fuel rail? Could be allowing the fuel to get past it and back down the return line, not letting the pressure build up. Or possibly simply a weak pump. I'd go rent a fuel pressure guage and see what's happening before I'd go to the trouble of modifying the control circuit. You're only treating the symptom, not the cause.

[bszopi]

Low fuel pressure won't cause the pump to continue to run after the car is off. From his initial description, it doesn't sound like the car is running poorly (which it would if there was a pressure issue), it's just that the pump continues to run after the engine is turned off. There are really only a couple things that could cause this to happen.

[geoffinbc]

The oil pressure sending unit may also be to blame. The sending unit is what provides the 12V to the pump when the car is running. Second the fuel pump relay should ONLY be on the when the ECM commands it on for 2 seconds to prime the fuel pump. So test this by turning on the key and seeing if the pump primes for 2 seconds then shuts off.

[Dave]

.. well the car is running great, fuel pressure is up there (I've already got a gauage for that)

the fuel pump does prime up at the initial hit of the key.

there's no leaks anywhere in the system, I just replaced all my O-rings on the fuel rail because it was doing this same thing before, then I changed the oil, the problem went away, and now it's back, so I'm thinking that it is the oil pressure sending unit.

Thank you for the help guys!

--Dave.

[geoffinbc]

Yea I'd suspect it too. Next time it does it remove the plug from the sending unit and see if it stops. If it does stop then the sending unit is staying closed for some reason keeping the pump on.

or just go ahead and replace it. Probabally 90% sure it is the problem.

[Dave]

yeah, I got the new part, I'll be puttin' it in later today (tuesday) hopefully that'll fix the problem - Tonight the strangest thing happened, I shut my car off, the pump stoped like it normally should, then I went out to my car 'bout an hour later, and the pump was running, I was like "Holy S#!T!" so I pulled the fuel pump fuse and decided that I'd better wait to work on it tomorrow, rathern then getting angry at it tonight.

Thanks again!
--Dave.

[geoffinbc]

LOL thats funny.

[Chug]

Im glad I looked at this. I have the exact problem with my 87 Cav, and I looked at the schematics and it didn't make sence but now with the explination of the oil pressure sending unit it makes perfect sence, I would have to say that is a good sugestion. I'll have to check that myself!!

(some of you might remember me hug311, I'm back fellas)
WHERE'S THE PARTY

[packardbell]

my fuel pump keeps on running after shut off as well.
pulled the relay and pulled the oil pressure switch but the fuel pump does not go out.
1988 cutlass supreme 2.8