What can anyone tell me about an 88' 2.9 not getting fuel. I tested pump & relay. They both work but Im not getting power to pump I really need some help with this. Any help would be greatly appreciated.

 

The fuel system is operated by the computer via the Fuel Pump Relay, it is not uncommon for this relay to fail.

Battery+ -------(fuel pump fuse)----Fuel Pump Relay-----inertia switch----Fuel pump-----Ground

The computer turns on the FP relay for 2 seconds only when key is turned on, it won't come in again until engine is started, just FYI.

On an '88 the Fuel Pump relay will be on the passenger side fender, it will have a Green Base that the relay plugs into.
EEC Relay has a Brown base.

Fuel Pump fuse is 30amp or it may use a Fusible Link in '88.
With FP relay removed test Base for 12volts in one of the slots, key off.
There should be 12volts all the time at that relay, if not then fuse or fusible link is bad.

inertia switch is in the passenger compartment, either under the glove box or in the kick panel.
It has a reset button on the top, this "switch" cuts power to fuel pump in case of an accident, these can fail and just cut power.

 

RonD,

If we were to troubleshoot this relay for correct operation, would we follow this?:

12 volts at the fuel pump relay fuse. If present, then check for 12 volts at blade 30 of the fuel pump relay (relay "feed"). Blade 85 would be this relays ground, and blade 86 at the relay would have 12 volts when the ignition key is in the on/run position (used as the "trigger" for this fuel pump relay to operate). Blade 87 (when relay is "on") would be the 12 volt output to the inertia switch, which then suppies the 12 volts to the fuel pump.

Would this be correct?

I guess I would first turn the key to "on", and check blade 87 for voltage. If I see 12 volts at this point with the key in on/run, the relay is working, and providing voltage to the fuel pump. If not, then I'd check the other blade points of the relay. If we have ground at blade 85, 12 volts at 86 with the ignition key in the on/run position, and 12 volts at blade 30 (from the fuel pump fuse), then the relay is bad.

Yes?

 

Socket 30 should be the 12v power from fuse/battery, but it could be socket 87 as well if wired that way, socket would have power 24/7(all the time) if battery is hooked up

85/86 are the relay's coil so one will be 12v with key on if relay is out of the socket, but both will be 12v if testing with relay in place, this is Key ON power

Computer ground is only active for 2 seconds so hard to test, and it could be 85 or 86, since it is just a coil it doesn't matter.
The 2 seconds part makes it hard to test, almost need a helper to turn key on and off