Mechanics

WHAT WOULD CAUSE THE FUEL PUMP FUSE TO BLOW EVERY TIME YOU TRY TO START THE CAR?

1988 Mazda RX7

The car will crank but wont start. Every time I check the fuse after I try to start it, the fuse is blown. So I keep replacing it.
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Emilyschultz
August 28, 2012.



"How many times are you going to replace the fuse before it occurs to you there must be a better way to figure this out"? That's what I ask my students. You know the next fuse is going to blow also. You can't expect anything else. Here's a trick that usually works: Replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.

In your case, unplug the fuel pump to see if the short is gone. If it is, replace the pump.

Caradiodoc
Aug 28, 2012.