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rollifd
Novice
Jul 15, 2010, 12:58 AM
Post #1 of 10
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'92 Trans Am Feul pump
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I have a '92 (mfg. in late '91) Pont. Trans Am with the 305 MPI motor... My problem is that if I let the car sit for 3-4 hours and try to start it it will run for about 2 seconds and die, and won't restart. I have power to the relays and ALL fuses are good but, NO power at the pump connector plug behind the rear seat. I also CANNOT find the "inertia" switch to see if it has tripped. Any ideas where the "inertia" switch is or why there is NO power at the feul pump connector plug behind the rear seat??? Also, does anyone know for sure which color the "hot" wire should be at the connector behind the seat??? I'm gettin' very frustrated (loaned it to my ex-wife and 3 days later I had to pay to have it towed back in). Any help would be greatly appreciated.......
(This post was edited by rollifd on Jul 15, 2010, 1:09 AM)
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Hammer Time
Ultimate Carjunky
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Jul 15, 2010, 2:35 AM
Post #2 of 10
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Re: '92 Trans Am Feul pump
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A couple of misconceptions you have............
First off, your car doesn't even have an Inertia switch. That is something used on Ford products only.
Second, you are not supposed to have power to the pump all the time. It powers for 2 seconds when the key is first turned on and picks up again when the computer sees a tach signal from cranking.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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rollifd
Novice
Jul 15, 2010, 10:55 AM
Post #3 of 10
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Re: '92 Trans Am Feul pump
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Ok... My bad... I was given the impression by one of the local area "mechanics" that it had an inertia switch... The reason I am trying to locate the main "hot" wire to the pump is so I can try to "jump" it and determine whether it's the pump or something else...
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rollifd
Novice
Jul 21, 2010, 6:19 PM
Post #4 of 10
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Re: '92 Trans Am Feul pump
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 Frustration is really starting to set in... Does anyone know witch color wire behind the back seat going into the pump plug-in is supposed to be the "hot" wire for the main pump power?
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Hammer Time
Ultimate Carjunky
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Jul 21, 2010, 6:30 PM
Post #5 of 10
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Re: '92 Trans Am Feul pump
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Gray hot, black ground
It only powers for 2 seconds when the key is first turned on and again when the computer sees a tach signal from cranking..
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Loren Champlain Sr
Veteran
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Jul 21, 2010, 6:39 PM
Post #6 of 10
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Re: '92 Trans Am Feul pump
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rollifd; The fuel pump circuit is controlled by 1) 20A fuse, 2) oil pressure, 3) relay. As HT said, you will only have power to the fuel pump for two or three seconds when you turn the key to the "ON" position. After that, it 'looks' for oil pressure from the oil pressure sending unit. No oil pressure, no power to the pump. Connect a fuel pressure guage to see if you have that initial 'burst' of fuel pressure when the key is first turned on.
Loren
SW Washington
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Hammer Time
Ultimate Carjunky
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Jul 21, 2010, 6:42 PM
Post #7 of 10
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Re: '92 Trans Am Feul pump
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It will power if it sees a tach signal or oil pressure builds up. It can operate without either one of them though. It only needs one or the other. The tach signal will be quicker.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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rollifd
Novice
Jul 22, 2010, 6:56 PM
Post #8 of 10
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Re: '92 Trans Am Feul pump
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Thank you to Hammer and Loren!!! That is the best info I have to go on yet... Upon testing I have power where it needs to be and the pump is definitely NOT running (I finally got a second set of hands to turn the key). Rats tho, I guess I have to just bite the bullet and replace the pump........
(This post was edited by rollifd on Jul 22, 2010, 7:07 PM)
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rollifd
Novice
Dec 15, 2010, 10:37 PM
Post #9 of 10
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Re: '92 Trans Am Feul pump
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 Just a quick update here... I replaced the fuel pump (which is a real bugger by the way) and still no run-run or vroom-vroom! Finally traced it on a whim tip from a mechanic buddy of mine... It was a bad temp sensor that read for the brain... It was causing an open circuit and the computer thought it's motor was -57 degrees and therefore doing a major choke-out job... As it turned out a simple $10.75 part from Auto Zone cured it all... Thanks again to everyone who tried to help... P.S.: I am signing my car up as a pitcher for the Mets as it throws great curve-balls...LOL...
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Hammer Time
Ultimate Carjunky
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Dec 16, 2010, 3:52 AM
Post #10 of 10
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Re: '92 Trans Am Feul pump
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You probably would have saved yourself a bunch of work if you had listened to Loren when he said to use a fuel pressure gauge to test the pump. Obviously it was working properly all the time. Changing that pump is no picnic on a Trans Am with the exhaust system in the way.
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