Early NA Blown Fuel Pump Fuse
06-28-2006, 11:22 AM
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Early NA Blown Fuel Pump Fuse
Hey guys I’m really just posting this for the archives.
I have an 84 NA that all of a sudden blew the fuel pump fuse. I replaced it a few times then started to investigate and isolate the source. It would blow immediately when cranking, even with the fuel pump removed from the circuit. Anyway, to make a long story short the fuel pump circuit is shared with the auxiliary air valve (black wire with a green stripe) as both get constant 12v. If the air valve binds up at all it draws enough current to pop the fuse. If you’re stranded on the side of the road you can unplug it and replace the fuse to get you home (this is the #2 16 amp fuse in the auxiliary block). If you free up the sliding plate inside the air valve (with a pick or screwdriver) it will stop blowing the fuse, at least until it binds up again. Over the years they can get nasty inside and develop some “junk” and if it gets caught between the plate and the body it will bind. The valve will check out fine with a meter and the natural inclination will be to replace the fuel pump so start by unplugging the AAV. Anyway, I hope it helps.
I have an 84 NA that all of a sudden blew the fuel pump fuse. I replaced it a few times then started to investigate and isolate the source. It would blow immediately when cranking, even with the fuel pump removed from the circuit. Anyway, to make a long story short the fuel pump circuit is shared with the auxiliary air valve (black wire with a green stripe) as both get constant 12v. If the air valve binds up at all it draws enough current to pop the fuse. If you’re stranded on the side of the road you can unplug it and replace the fuse to get you home (this is the #2 16 amp fuse in the auxiliary block). If you free up the sliding plate inside the air valve (with a pick or screwdriver) it will stop blowing the fuse, at least until it binds up again. Over the years they can get nasty inside and develop some “junk” and if it gets caught between the plate and the body it will bind. The valve will check out fine with a meter and the natural inclination will be to replace the fuel pump so start by unplugging the AAV. Anyway, I hope it helps.
06-28-2006, 11:36 AM
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On the the 86 turbo, the oxygen sensor shares the fuel pump fuse. I had a car that kept blowing the fuel pump fuse, and I couldn't figure out why. So I checked the wiring diagrams, and sure enough they shared the same fuse. It turned out the oxygen sensor wire had melted on the crossover pipes, and the wires were shorting out, blowing the fuel pump fuse. Crazy eh.
