Fuel pump wont shut off.... EVER help!

i just bought another cherokee yo use a daily drive and i cant figure out why the fuel pump will not shut off. I can pull the relay, and it still continues to pump. It will pump with the ignition off and key out, the oply way to make it stop is to pull the negative terminal on the battery. any sugestions? please help, this is driving me crazy.
thank you
Bob

Pull the ASD relay.

'Sounds like somebody (some idiot?) hard-wired the pump. Start at the gas tank and work your way forward on the wiring harness. Should be pretty easy to spot where the harness was butchered.

tbburg said:

'Sounds like somebody (some idiot?) hard-wired the pump. Start at the gas tank and work your way forward on the wiring harness. Should be pretty easy to spot where the harness was butchered.

Click to expand...

Very possible as you just acquired it, but pull the ASD first, if it is stuck it will cause your problem.

I forgot and left out that I have pulled that relay also. Sorry. Also it isa 95 cherokee sport if it matters. And I looked but cannot find where the harness could of been hacked. I'm lost. I'm to the point where I think I'm gonna hack it and run a realay
.

On the Renix there are multiple paths for the fuel pump power. I don't know on the OBDI/II.

Renix:

Turn key to ON, power to the fuel pump is through the B latch relay (later model ASD relay), this bypasses the ballast resistor (eliminated in 94) and provides 12v to the pump.

Turn key to START, power to the fuel pump is through the starter relay, this bypasses the ballast resistor (elim. 94) and provides 12v to the pump.

Engine running, power to the fuel pump is through the fuel pump relay and then through the ballast resistor (elim. 94) where it is reduced to about 6v.

Engine running, throttle at wide open, power is through the oxygen heater relay, bypassing the ballast resistor (elim. 94), and provides 12v to the pump.

As this is for the Renix, I don't know if it will be of any use to you, but I hope it may get you started.

i had this happen to me with my 95' XJ, ended up to be the relay itself. pretty weird as this only happen to me once, soon as i removed the relay, it unstucked then work fine since

id remove the fuel pump relay and check voltage on the terminals (the power side, not the switching side) to see if its getting some voltage on both side, id suspect that wire somehow got B+ from somewhere

OK this may be a very stupid question, and please no burning, but are you sure its the fuel pump running after you pull the relay? Have you tried just unplugging the pump itself to make sure it shuts off from the source?

Yes, its definitely the fuel pump. No doubt about it.

If you can't find where it was messed with, you could check at the fuel pump relay to see if it is powering up and down like it should. If it is, run a new wire from there to the fuel pump direct. But I would sure try to find what the PO F.U. before you got it. Does the gage work right?

Yea the gauge works fine... Thanks everyone for you help. I'm just gonna put a relay on the power wire, and power it by ignition.
Thanks a lot.
Bob