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Fuel pump fuse blows when engine is turn off

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Old 05-05-2014, 04:51 AM
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Fuel pump fuse blows when engine is turn off

Car is a 1987 GTA, 305 TPI.
As topic, the car starts and runs just fine. Thing is, when I turn the engine off , the inline fuse in the battery area goes *pop*. I've tried disconnecting both the MAF and the MAF burnoff relays, did nothing. I've also tried switching the connectors to the relays, so it shouldn't be a faulty relay.
Could the fuel pump being defective cause this?
Old 05-05-2014, 07:10 AM
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Re: Fuel pump fuse blows when engine is turn off

The pump and the MAF relay are killed when the key is turned off

http://92b4crs.tripod.com/86wiring/dia-pics/22-2.jpg

Only the burnoff relay is powered up so that circuit would be the one I would be looking at for a direct short to ground somewhere

http://92b4crs.tripod.com/86wiring/dia-pics/22-5.jpg
Old 05-05-2014, 08:08 AM
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Re: Fuel pump fuse blows when engine is turn off

Thanks a lot for the answer, turns out the problem was pretty simple. Right before I put it away for winter storage, I used the SES light to check some error codes. Turns out I forgot the paper clip in the ALDL connector, which for obvious reasons caused short circuit when the engine was turned off

Oh well, it only took me about 15 fuses to find out...
Old 05-05-2014, 11:04 AM
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Re: Fuel pump fuse blows when engine is turn off

Originally Posted by F_Jaeger
Turns out I forgot the paper clip in the ALDL connector, which for obvious reasons caused short circuit when the engine was turned off
Nope ..... No way possible if you had the ALDL properly jumped to display codes , would it blow that fuse !

Now I realize that maybe the fuse stopped blowing at the same time you found the forgotten jumper , but if the two were REALLY related that would mean that anyone else with a similar car who forgot the jumper would ALSO blow the same fuse in the same situation . But then , NO ONE but you has reported such (and yes , I did search !) and so I believe that either you didn't have the ALDL jumped properly , OR , that it was a coincidence the fuse stopped blowing then (jiggle any wires or anything between the last blown fyse and the found jumper ?) .....

Just for grins , exactly which two ALDL pins did you have jumped ?
Old 05-05-2014, 03:48 PM
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Re: Fuel pump fuse blows when engine is turn off

Well, the jumper was probably connecting two other pins than those required to flash the error codes. I really don't remember which ones, I just grabbed it and ripped it out.
Old 05-05-2014, 07:11 PM
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Re: Fuel pump fuse blows when engine is turn off

Originally Posted by F_Jaeger
Well, the jumper was probably connecting two other pins than those required to flash the error codes. I really don't remember which ones, I just grabbed it and ripped it out.

I looked at the wiring diagram for both the ALDL and the fuel pump . If you had mistakenly jumped the fuel pump test port to ground that would certainly explain the blowing fuse . But then , with the fuel pump rather than the proper ALDL pin grounded it couldn't have been flashing any codes .

..... Unless you had more than just the one jumper ???
Old 05-05-2014, 07:27 PM
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Re: Fuel pump fuse blows when engine is turn off

Had that problem once, but I was using a back up power switch to FP, it was a lighted switch, the grounding for the tiny light in the switch would pop the fuse every time.
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