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1989 GT Fuel Pump/Inertia switch

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Posts: 1
Joined: 02/10
Posted: 02/13/10 03:25 PM

Car just died. I have replaced inertia switch, and fuel pump relay. I ran 12v to the pump, and I know it is bad. The question I have is I am showing 6v at the new inertia switch, but when tested, I do get 12v momentarily when I turn ignition on, but then it drops to 6v. One mechanic told me that the computer senses the motor is not running, and it will automatically make it 6v from 12v at the inertia plug. Basically, all I need is a new fuel pump. Does this make sense? Thanks, Jeff.  

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Posts: 194
Joined: 02/10
Posted: 02/14/10 11:30 PM

most of the EFI motors were wired kinda strange..   the efi main relay also powered the fuel pump relay winding..  teh power for the relay power circuit comes usually from the ring terminals on the starter solenoid..

so you might really want to either replace the efi main relay.. or measure the voltage on its output..

one thing... dead fuel pump  can almost always be started by 2 people..  one cranking the motor.. while the other pounds on the bottom of the fuel tank..  works about 90 percent of the time.. since the fuel pump only gets powered while you are cranking the motor.. and once the engine starts...

how clogged is the fuel filter???    that will take the pump live out..

here is the link to a 5.0 wiring diagram..   the fuel pump relay and efi main relay are in the upper left corner..


with the key on to activate the efi main relay..  you can ground the tan and light green wire at the EEC connector.. and trigger the electric fuel pump relay....  but i would check the orange and light blue wire from the starter relay ...

its so much easier with a proper wiring diagram..  

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