lumley8788

Just bought a 1993 Cherokee country in non running condition. Im able to spray carb cleaner in throttle body and it will start. checked for power at the pump and I have 6v on the center wire. When cycling the key I never see the 2-3 second 12v prime. I bypassed the resistor and no change on voltage. Checked and swapped the relay with starter relay still no change. Is it only supposed to have the 6v signal and not the 12v? the fuel gauge is not working either. This jeep has been sitting for a long time so Im assuming the pump has froze up and the sender is shot too just trying to make sure before I throw parts at it. any help would be appreciated Ive been looking around for the answer but having issues getting a straight answer or approach to do next.

lumley8788

*****update******* went out and tried some things ive read to try, I jumped 30 and 87 and bypassed the resisitor I now have 12v at the resistor and back to the pump. still not working (which is fine I assumed the pump was shot) but the other question I have now does that mean the PCM is no good and not letting power get from 87 to 30? With the key on and the relay removed I have power on 3 out of the four terminals. If I put a jumper in I get juice. any additional help would be appreciated THANKS!

Pelican

I went through a somewhat similar situation with my '93 and about went nuts. As a final act of desperation I put a dab of Ox-gard on each of the new relay terminals and plugged it in. The thing started and has been running ever since (about 5 years). I don't consider this a "fix" but I'm afraid to unplug the relay to find out. Maybe the Ox-gard cleaned off a bit of corrosion although you would think that all the relays I had plugged in would have done that already.

You should have 12 volts to the pump at start up. In stock configuration it is then switched to 6 volts (or whatever) through the resistor. You can permanently bypass the resistor just to take it out of the equation. It presumably is only there to quiet the pump when running.

People talk about a 3 second prime but my '93 has never primed for more than a second and almost always less than that. Assume you have replaced the fuel filter?

You probably know that you can press the schraeder (sp) valve on the fuel rail to confirm that there is no fuel pressure.

Probably preliminary for you at this stage, but it is easy to add a check valve on the '93 near the filter to prevent drain back into the tank. Mine holds pressure for days and maybe that is why I get such short primes.

Just some thoughts.

Edit: Amazing! You post while I'm composing.

Pelican

This doesn't answer your question but as I said, I would permanently bypass the resistor to get it out of the picture. You can always "un-bypass" it later after everything works.