Ok this is probably going to be a long one. I have a 91 Cherokee Sport 4.0L, That recently had the Bendix 9 ABS system on it. I tore out all of the system for a non-ABS out of a 86 cherokee(the booster pump went out and stealership would not do it), no problem with that, had a leak so I fixed it. When I went to start it for the test drive it would not start, It had no fuel pump startup when the key was turned(granted I was the first to change it, it needed it) changed it out still no startup from the pump when the key was turned. Started doing some tests, checked for spark, none, and checked for pulse in the injectors none there either, there is also no voltage at the ballast resistor or when the wires are shorted together. I don't have a clue what could have happened it was running fine that morning.
Have already replaced CPS sensor and still did not start, or fuel pump prime.

Could it be a bad computer, I read on some other threads that the CEL will not come on when the key is turned, mine is not coming on. Is that a symptom of it.


Thanks in advance

91 Cherokee Sport AW4 4.0L HO (not renix)

mine did the the coil pack or could be the dohicky inside of the distributer at the bottom but check the coil

Would that cause the fuel pump to not prime when the key is turned?

If there is no spark, there wont be any fuel. Need the spark signal first in order for any fuel to be pumped in.

i gotta disagree. the fuel pump will prime regardless of spark. and if you have a bad coil for example, you will still have fuel pressure. and at first it did sound like a cps untill you said the pump didn't prime. i'm assuming you checked all the fuses. if no lights light up for the bulb check with the key on for the first few seconds thats a sign of an ignition switch. do you get any of the bulbs for the first few seconds? if not, i'd say switch most likely.

when the switch goes out, its not even switching any signals to the ecm or anything so no spark, fuel prime or pump, no pulse, and it will still crank, thats a seperate part of the switch that rarely goes bad.

AHHH Thanx for the correction. I didn't catch that part. How about that pick up coil on under the cap on the distributer or oil pump deal?? I'm sure you know what I'm talkin about. Like a cam sensor.

its a cam sensor, usually to replace it just do the whole distributor. it is possible, that will cause no spark, and no pulse, but that will not cause no fuel pump prime. between that and the no bulb check thats why i'm leaning toward switch, or maybe just a fuse, the ignition main fuse, or another.

reading this again i forgot to say my main problem here. 99% of the time if you just did something, and something else goes wrong, it will have to do with the first thing. there are rare coincidenses that will drive you nuts. but go back to what you did. you have all the signs of a bad ignition switch, or a blown fuse. possible something didn't get connected, or a wire got shorted and popped a fuse. always eliminate the possibility of what you just did before moving on to other bad parts.

good luck and let us know what happened.

Yeah, that does make sense.

jpdocdave
There is one light that does turn on the seat belt light
I have went over everything, every fues, switched relays and I still haven't seen anything out of place, It ran fine right before I fixed the leak in the new brake system, and that was after the first test drive.
Where at would that switch be, Is it right behind the lock cylinder or is that the one that is under the dash somewhere. and are you talking the ICM?
I have checked every fuse in the thing and all are good, unless there are hidden ones that cannot be seen without looking under things, in which where are they.
Is there are way to check the switch to be sure, I have already spent more than I expected and don't want to be guessing still.

you can check the switch with a wiring diagram and a test light. you need a constant 12 volt supply, a ground, and then you need a diagram to know which wires are powered up or ground with the key being turned. i can't remember exactly on xj's, but the switch should be in the column, yours is older so it is probably an old style switch on the under side of the column.

have you checked your relays also, i would double check the ignition fuse, and go from there.

pick up a haynes manual for your xj if you haven't already or any decent manual, the wiring diagrams are great to have.

I did a lot of checks on every thing I could find, the only thing I did not have voltage to is the ballast resistor and relay, and all subsequent systems attached through grn/blk wire, there also is no voltage at the ECM either, which says to me the ecm is fried? Wouldn't it still throw a code 11 (battery power disconnected from PCM) if the ecm was ok? I do have a haynes manual that I have been using constantly for wiring diagrams. I am at wits end on this thing!

Being where you were work, start by check the Crack Position Sensor, Check to see if it's plug in and make sure you didn't pinch the CPS wire. I did this when doing tranny work and had teh very same issues your having. It causes a ground circuit adn nothing will turn on at all.

I'd say start there..

Is there a specific voltage that the CPS should have running to it from the harness, I am getting less than .5 volt on two of the pins and nothing on the third one, that is with the key in RUN position?

I changed the cps after all of this was done, and have not been near any of that since.

I was wondering if there are any fusible links in the harness on that side of engine compartment, that lead to the ECM, specifically for the ballast resistor, that is really the only place that I should have 12 volts and have none. I wasn't really clear on the last post, I have voltage to ECM, but not to the grn/blk wire that is for the Ballast resistor. sorry for mislead.
The reason I was wonder about the ECM fried, I have no CEL on turning the key, and have had the ground cable taken off for overnight, and it still never showed a CEL.

have you checked for voltage being switched from the ignition switch?

you will not have any voltage coming out of the ecm if the switch is bad, and the computer doesn't know the switch is on.

i do agree with checking for pinched cps wire, i've seen that happen a few times.