My old truck has a problem with zapping alternators.

It's a 1990 F-150 with a 5L V8.

Specifically, I believe the voltage regulator is going out. Giving it a lot of gas seems to always be the event that causes it to pop, then the battery gauge slams over to max and the battery light blinks. After a few miles, the battery light goes solid and after that it won't start.

Might be unrelated, but the cycle started after I had a couple of clogged fuel injectors cleaned. This caused a big uptick in power.

My only guess it's it's a wiring problem, but I don't know where to look. Until the issue happens with the battery gauge, the alternator works fine and keeps a strong charge on the battery.


I would check the grounding straps, engine to body, engine to battery or body to battery.

On some vehicles they are fitted across the gearbox mount - shorter so cheaper...

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