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Fuel pump runs after car is shut off

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Old 05-24-2014, 06:06 AM
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Car: 86 T/A, 89 Formula
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Fuel pump runs after car is shut off

Guys this could be normal but I have not run onto this before. I have a 89 305 TBI last night I was coming home from work and running low on fuel, I was backing into my drive way which is on a slant and ran out of fuel. " yah I know why didn't the idiot put gas in it before I come home " OK.. later on I am out working on the car and I hear the fuel pump prime So I waited and about three minutes later it did the same thing. Does the fuel pump have power at all times? I have not heard of this...
Old 05-24-2014, 10:47 AM
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Re: Fuel pump runs after car is shut off

Sounds like a short somewhere. Normally the pump will run for a couple seconds after the engine is shut off because the oil pressure switch remains closed until the oil pressure drops below 15 PSI. If it's running intermittently in the prime cycle with everything off, I'd look for a short to power in the ECM ignition power wiring. Or worse, another ECM because it may be shorted internally if no wiring is damaged.
Old 05-24-2014, 04:44 PM
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Car: 86 T/A, 89 Formula
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Re: Fuel pump runs after car is shut off

Thanks for the info Dan. I put in a new ecm about six months ago. I'll check for a short this weekend. could a ignition switch cause this problem ? it's been kind of loose lately.
Old 05-31-2014, 01:45 AM
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Re: Fuel pump runs after car is shut off

I just had the same thing happen to me after I changed the oil pressure switch. The new one had a short. A quick trip to Autozone to exchange it for a different one solved it.
Old 05-31-2014, 06:15 AM
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Re: Fuel pump runs after car is shut off

That's where I eventually found mine. It's hard to chase down a short that comes and goes . I'm just glad I didn't have to pull the fuel pump. I hate that job in these cars! Makes me wish I owned a 80's mustang ( OOPS dirty word ) I wouldn't trade my "f-body for a mustang any day". Have you guys seen any thread on cutting a hole in the trunk to access the fuel pump? I know where to cut , I was mostly looking for neat ideas to make it look good when I'm done changing the pump. Thanks guys for your info and for sending me in the right direction "Dan" .
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