Fuel Pump Run On

[Ira M]

My battery was dead this morning on my 1990 Transport and it sounded last night like the fuel pump was running on after the engine was off. It was a humming sound coming from the back of the vehicle and I am guessing it was the fuel pump. I think this has happened to me before. Last night I also rear ended a car in front of me on winter ice, if that has any connection. There wasn't much apparent damage to the vehicle.

What makes the fuel pump run on like this and is that likely what it is?

[DonSor]

In most automobiles, there's a collision/impact switch which if you get into a collision, will automatically shut off the fuel pimp but can be reset. If anything else, your fuel pump shouldn't be running at all. Having a fuel pump running after your ignition is shut off is dangerous. One possible problem is with your ignition switch whereby it's stuck in the start position (that is the position before cranking the engine in which the fuel pump starts in preparation to move). Does this happen all the time or just intermittently. Noentheless, unless your are knowedgeable in the electrical troubleshooting you better get a good mechanic to check this out.

[Ira M]

Originally Posted by DonSor

In most automobiles, there's a collision/impact switch which if you get into a collision, will automatically shut off the fuel pimp but can be reset. If anything else, your fuel pump shouldn't be running at all. Having a fuel pump running after your ignition is shut off is dangerous. One possible problem is with your ignition switch whereby it's stuck in the start position (that is the position before cranking the engine in which the fuel pump starts in preparation to move). Does this happen all the time or just intermittently. Noentheless, unless your are knowedgeable in the electrical troubleshooting you better get a good mechanic to check this out.

Thanks for your info. Ira M.

[LMP]

DO you have an automatic load leveler? THis accessory is HOT all the time and if you have a leak in the air shock or related tubing, and specially if the car has a heavy load - but not necessarily - then the air pump will try to level the rear and the pump will run all of the time if there is an air leak. But also, the level sensor can be toasted (above the center of rear axle) or linkage can be damaged and keep the pump running. Just unplug the wiring from under and better forgetr about it...very expensive. (but I replaced my danaged setup with a 10$ tire inflater....instead of the $1000 they were quoting. Rêplacement air shocks are available from Monroe....but Gabriels are a no-no)

As for fuel pump, there are 2 feed modes: at key on, a relay clicks in. Sometimes relay contacts will melt and bond and not release once energized SOlution: replace relay. ALso, fuel pump is kept ON as soon as oil pressure switch detects 5 psi. A defective oil switch (less probable) can cause that problem.

By the way, the fuel pump is almost in the center of the car,while the load leveller compressor is fully rear behind the left wheel well.

[sdsumike619]

LMP, do you mean the Oil sending unit when you say "oil switch" ?

[LMP]

Yes the sender has 2 parts (4 contacts) : a sending unit and a pressure switch that keeps the pump on as oon as some pressure builds.
www.avigex.ca/xport/fuelcontrol31.jpg
I suggest you disconnect the oil sending unit..you will loose oil pressure indicator but you will see if this is what keeps the pump running....
Also check that fuel pump relay up front
www.avigex.ca/xport/relays.jps