mlp141

Hi guys -- my neighbor's 16-year-old has a 1990 F-350 with the 7.5 gasoline engine. There is an electrical drain somewhere that keeps killing the battery and he's not sure where. He's chased down a few gremlins but not the culprit. What he's done is installed a battery cutoff to stop it from draining over night but that will not solve the problem.

I was over there giving him a hand tonight and when he turned the battery back on, I heard the fuel pump whir. But, the keys weren't in the ignition. According to the Haynes manual, the pump shouldn't come to life until the key is inserted and turned to the "on" position. Once the battery is connected the pump doesn't run continuous or anything, but it doesn't seem right that it kicks on without the key.

Could this be the draining the battery? There is no fuel pump fuse that we could find; there is a fuel pump relay and that was replaced. He kept the old one and when we reinstalled it the results are the same.

Just looking for some input. He's a great kid and I'd like to help him out.

Thanks.

88xlt

The fact that the fuel pump whirs when the battery is connected makes me think maybe the ignition switch isn't completely shutting off. Maybe other stuff that runs off the ignition switch is running the battery down. It may just be a misadjusted ignition switch. There is a rod that connects the key tumbler with the actual electrical part of the ignition switch. The switch slides back and forth for adjustment.

For troubleshooting I would turn the key back on acc as far as I can, then connect the battery and see if you hear the whir.