Mr. Clean

What is the PCM? And where is it?

cherokee77

PCM is ECM it is the computer to control engine. It is underneath the dash right above the gas pedal.

Shade133

ok so we've ruled out spark and compression, you can start the vehicle if you give it fuel somehow.

do this next. check the ballast resistor for the fuel pump for good connection or if it even works.

its on the driver fender in the engine compartment. take the 2 wire connectors off and bypass the resistor by connecting the 2 wires with another wire.

now turn the key on and try to start the truck. if it starts and runs. replace the ballast resistor. (do not drive it like this because you'll ruin the fuel pump. the reason its there is to lower the voltage on the fuel pump to keep it cool)

here is a picture of the ballast resistor.



its the white thing on the right.

let us know if this helps.

useitorlooseit

what year is your xj 97 and up its beside the air filter. when the key is in the on position it will start the pump for a few seconds then automatical turn off. this is when someone should go under neath and check the wires on the pump for power using a separate ground ie. the frame. if you dont have power while someone inside the vehicle is keyin it on and off in 3 second cycles then thats your problem. if you do have power now check the ground between the power wire on the pump and the other wire the ground wire. if you dont have ground you need to get a wireing diagram. is there power and ground?

AnotherBoss

The Cherokee started, it was a fuel line, it was totally busted.

Mr. Clean

It was a fuel line in the tank, the one that go's from the fuel pump to the pick up line. Completely wore out!

Thanks to everyone for all of your help and input, it made this frustrating job much easier.

Mr. Clean

We now have another problem, I hope it's not a hard one!

I can't bring the idle down any lower than 2100 rpm? Thats even after running for 15 min.

Shade133

tps?

or the idle air control valve is stuck.

only 2 things i can think of to check.

most likely its the IAC.

Mr. Clean

I adjusted the TPS again, and got it set to .830vdc, then unplugged the MAP and plugged it back in, now all is good. It has an idle speed of 500-650 RPMs now.

Thanks guys for all the help once again!

Mr. Clean

Just took the Xj for a smog, no problem passing at all!!!! The Tech said that it was running like new.

This is the best ending I could ask for to this thread.

Shade133

lol nice!

but i have a question. you got your tps to be at .830 volts when the throttle is closed?

mine is at like 3.5 volts when the throttle is closed lol

Mr. Clean

YA, .830 vdc fully closed. This is supposed to be the prime setting. Did you adjust yours or is it just set at that voltage?