PCM issue

[Dmill1369]

Ok here's the issue i'm having gents. I'm on my 3rd PCM. keeps loosing the fuel circuit. when installing new PCM it will fire and run once, after i turn it off no more love from the PCM. All the wiring appears to be fine, new relay, pumps are both fine. inertia switch isn't tripped. any ideas on what the f*** is going on?

i also have two free switches in a 6 panel, could/should i just bypass the PCM and wire the pumps up that way? I have a fuel cell i plan on plumbing in in the future, just would like to have the truck driveable in the mean time.

 

[85_Ranger4x4]

What engine do you have? I assume this is your '88?

 

[Dmill1369]

its a 2.9 V6.

 

[adsm08]

You can hot wire the fuel pump that way. You will just need to remember to turn it on and off each time.

It will remove a level of safety as the computer disengages the pump if the engine RPM drops too low. It's a fail safe, in case the inertia switch doesn't trip in an accident, if the engine is stalled by the impact, or a fuel line gets cut and stalls it, the computer shuts the pump down.

 

[Dmill1369]

what would be the best way to do that? just tap each pump near the connector and run a hot and ground? or tap it at the relay?
should be easy to remember to turn off, i have an electric fan on switch as well.

 

[adsm08]

I would cut the tan/green wire (pin 22) at the computer, extend it across the inside of the cab to your switch, then ground the other side of the switch.

This will leave the entire rest of the circuit intact.

 

[85_Ranger4x4]

I have mine (aftermarket pump) ran off of keyed power so it turns on and off with the key like everything else. I also have an inertia kill switch in it just in case.

A toggle switch would be a good anti-theft measure to have in the mix too if you have open ones.

 

[Dmill1369]

Excellent, thanks for the input.

 

[Dmill1369]

I have mine (aftermarket pump) ran off of keyed power so it turns on and off with the key like everything else. I also have an inertia kill switch in it just in case.

A toggle switch would be a good anti-theft measure to have in the mix too if you have open ones.

i'll be ditching the inertia switch as well, can't imagine the headache it will be once my build is finished and i go crawling. i'm just going to run the pump off a toggle, ive got two spares in a 6 gang panel that's all set up and grounded already.