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Fuel Pump doesn't prime. How can I check if the pump is bad?

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Old Aug 7, 2014 | 02:37 AM
  #1  
Blaze of Glory's Avatar
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From: Bay Area, CA
Car: 92 Firebird
Engine: 3.1L V6
Fuel Pump doesn't prime. How can I check if the pump is bad?

My car wouldn't start when I got off work. I had to call a tow truck. It worked fine in the morning.

Eventually I realized there is no fuel pressure by pressing on the Schrader valve of the fuel rail (nothing comes out). Also, I don't hear the whine from the fuel pump when I put the key in the on position.

What's the easiest way to check if the pump is bad or if it's an electrical problem? I've seen other posts where they check voltages on the ADL (what's the ADL?) and /or short the relay.

If I do need to replace the pump. Should I consider cutting an acces hole in the hatch?
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Old Aug 7, 2014 | 01:47 PM
  #2  
Gumby's Avatar
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From: NWOhioToledoArea
Car: 86-FireBird
Engine: -MPFI
Transmission: T5
Axle/Gears: 3:42
Re: Fuel Pump doesn't prime. How can I check if the pump is bad?

the pump will prime if you reach 7psi of oil pressure, which might mean you need tocrank it 2-3 times to build said pressure.

If that doens't even work, its broke. but check the fuse in the right nose of the car. youll find it, single weather packs holding a fuse.

Of course put in a proper door, youll kick yourself if you have to go back in........
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Old Aug 7, 2014 | 01:58 PM
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From: Florida
Car: 1989 Camaro RS
Engine: LH6
Transmission: T56
Axle/Gears: 3.42 Auburn Posi
Re: Fuel Pump doesn't prime. How can I check if the pump is bad?

Originally Posted by Gumby
the pump will prime if you reach 7psi of oil pressure, which might mean you need tocrank it 2-3 times to build said pressure.

If that doens't even work, its broke. but check the fuse in the right nose of the car. youll find it, single weather packs holding a fuse.

Of course put in a proper door, youll kick yourself if you have to go back in........
Not always. The ECM can also be the issue. I had the transistor that controls the fuel pump fail on mine.

Also, if you have a faulty oil pressure switch plug that in, that will fire the fuel pump.
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Old Aug 7, 2014 | 03:54 PM
  #4  
Blaze of Glory's Avatar
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From: Bay Area, CA
Car: 92 Firebird
Engine: 3.1L V6
Re: Fuel Pump doesn't prime. How can I check if the pump is bad?

So what's an easy was to check if the fuel pump is getting power? At the relay? If the pump isn't getting power I'll have to start looking into the ECM and oil pressure switch.
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Old Aug 7, 2014 | 04:40 PM
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: Fuel Pump doesn't prime. How can I check if the pump is bad?

At the relays under the hood by the brake booster, look for a short red wire with a fast-on connector on the end. Connect a wire to it then to the battery + terminal. This is with the ignition key-off.

If that runs the pump then the wiring at the relay back to the pump is OK. Plus the pump is OK.

That is the one of two quick tests that is helpful.

The second is to be sure that the SES or CEL light on the dash turns on at key-on, engine-off. If it doesn't then it is likely that the under-hood inline fuse popped (it happens).

RBob.
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Old Aug 7, 2014 | 08:29 PM
  #6  
Blaze of Glory's Avatar
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From: Bay Area, CA
Car: 92 Firebird
Engine: 3.1L V6
Re: Fuel Pump doesn't prime. How can I check if the pump is bad?

So, I tried starting the car this morning before work and there was nothing. Just cranking. I thought I would give it another try this evening before I started diagnosing and the car started right up. It was a $200 tow last night to get home.

I suspect something is still wrong. I can hear the fuel pump chattering a bit when it primes. I could swear it was only a whine before.

I hooked up a fuel pressure gauge at the rail and confirmed that the pressure is quickly fluttering between 40-50psi while it's priming. I connected the fuel pump prime connector to the battery and the fuel pressure flutters like crazy between 40-50.

I can't remember if this is normal or not. Can someone chime in?
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