wiring problems

[tronco]

I was wondering if anyone could help me out? I have a 88 ranger with a 2.9, 5 speed 2 wheel drive. Problem is my fuel pumps will not come on with key, I replaced both pumps and relays . I have a freind with a 60 pin breakout box I can use but have no wiring chart . thank

 

[Psychopete]

I was wondering if anyone could help me out? I have a 88 ranger with a 2.9, 5 speed 2 wheel drive. Problem is my fuel pumps will not come on with key, I replaced both pumps and relays . I have a freind with a 60 pin breakout box I can use but have no wiring chart . thank

What do you hear when you put the key on 'Run', can you hear the relays click, or is it dead?

The computer controls the fuel pump circuit. The computer relay is the path where the switching side of the relay gets +, it's gets ground from pin #22 on the PCM (to turn on fuel pump relay).

You might check a few things - Is the computer actually turning on (check yellow wire at pin #1, also pull codes)? Is the ignition switch functioning properly? Is the fuel pump or computer fuse blown?

It makes a lot more sense looking at a wiring diagram, it would make things a heck of a lot easier to diagnose since you'll be able to see the path of each of the circuits - even a Hayes manual would be better than hit and missing if you're not fimilar with it, but just don't trust it 100%.

Pete

 

[tronco]

pumps dont come on at all, but they will if you jump it at test port . also i have power at the relays fuel and eec but nothing happens with key on. I cant get it to give me any codes

 

[shadetree]

If you checked the pumps at the test connector, that is the same thing the computer does, grounds this circuit, closes the fp relay turning on the pumps.
It tells you the wiring, inertia switch, pumps, grounds are ok from this point back to the tank.

My next step would be to check the wire going to pin 22 of the computer from the fp relay for continuity. Use an ohm meter, or continuity tester. This is a tan/ltgrn wire. If the wire checks good, you have a computer problem. It is not grounding pin 22 closing the relay. Of course, if the wire doesn't show continuity, there is a problem with the wire going back to the relay.

You can also check this wire with a voltmeter. Disconnect the plug from the computer, turn on the ignition, and if you have battery voltage at pin 22 of the computer connector, the circuit is good, confiring computer problem.

Make sure computer has battery voltage at pins 37, and 57. ignition on.shady