Fuel Pump Relay Circuit

[jeepersmitty]

New to working on a Mustang, so even the most basic help is welcomed. 1990 2.3l Fuel pump problems. If I bypass the relay under the drivers seat, the pump will work and the car will start. When I check the imputs to the relay, no signal. Where does the signal come from? Is there a pressure switch on the EFI that turns on the fuel pump relay. Does it go to some computer. If so where is the computer and what are the pins? Thanks for any help.
Jeepersmitty

 

[351wcoupe]

New to working on a Mustang, so even the most basic help is welcomed. 1990 2.3l Fuel pump problems. If I bypass the relay under the drivers seat, the pump will work and the car will start. When I check the imputs to the relay, no signal. Where does the signal come from? Is there a pressure switch on the EFI that turns on the fuel pump relay. Does it go to some computer. If so where is the computer and what are the pins? Thanks for any help.
Jeepersmitty

Just so I understand?.....
you're jumping the "hot" wire and the ground wire at the fuel pump relay? correct
the "on off" part of the switch is controlled by the ECM I forget the pin number I'll get that in a minute for you.
quick questions...
Are you sure your relay is good?
Is your inertia switched flipped? (shouldn't cause this problem but its part of the circuit)
check for power coming from the computer pin..

 

[351wcoupe]

It should be computer pin # 22.
When I wired amanda's car for the swap that pin pushed itself out of the connector and would turn the pump on.