Fuel Pump running continuously

I have a 1996 Bayliner 2452 wi

I have a 1996 Bayliner 2452 with a single 2004 Mercruiser 5.0 MPI with an OM300000 series serial number. Today I anchored to fish for Halibut here in Alaska and the fuel pump would not stop running even after turning off the key. The only way to stop it from running continuously was to turn the battery selector switch to off. I immediately pulled anchor and went to the pier. Once again after shutting off the engine the fuel pump stayed energized. Normally when I turn the key on the pump runs for a few seconds then shuts off. Any help would be greatly appreciated.

"Did everything else shut off

"Did everything else shut off normally when you turned the key to off? Guages dead?
It sounds a lot like the engine harness is staying powered up with the key off, and that is just weird.

Rod"

Something shorted at the key s

Something shorted at the key switch or defective key switch?

"Everything else shut off norm

"Everything else shut off normally, the gauges went to nil and all else (that is supposed too) went dead."

"Just checked the wiring diagr

"Just checked the wiring diagram (page 4D-7 of Sm 31). The fuel pump is controlled by a relay that is mounted just behind the Ecm on the port side, just inside the edge of the exhuast elbow. There are 2 relays; one is main power and the other is the fuel pump.

The fuel pump relay has 4 wires: drk grn, pink, pink/grn and pink/yell. It may be fried in the closed position, such that the pump keeps running even when the relay is shut off. Pull the relay and check for continuity between pins 30 and 87. These are pink/grn and pink/yell wires respectively. If these pins ON THE RELAY are closed circuit, the relay is fried.

That's all I can think of. When the Ecm is powered down, the energizing circuit to the relay (pins 85 & 86) should also be dead.

Here is a simple test. Duplicate the condition of pump running with the key off, and tap the relay case with the handle end of a screwdriver. That may be enough to break the fried contacts loose and stop the pump. If it works, replace the relay anyway, as it will surely fail again.

Rod"

"and be thankful it failed clo

"and be thankful it failed closed, not open "

One tap and the pump shut off.

One tap and the pump shut off. I will be replacing it ASAP. Thanks for the advise.

Sounds like you found it. Good

Sounds like you found it. Good news.
Let us know how it works out..

Rod