No injector pulse
 

I have a 94 Cherokee, 4.0, just purchased and it started up when I bought it, brought it home on a trailer because the xfer is kaput, now it wont start or attemp to start, but engine rotates, there are no check engine light codes, just the normal 12, and 55, I have since changed the spark plugs, cap, and rotor, I have 40lbs of fuel pressure at the rail, I have spark at the spark plugs. I did hook up a noid light to one of the injectors connector, and when engine rotates there is no light, I am not sure if this is normal or not, when I pull the plugs after cranking they are completly dry. any suggestions thanks in advance.

Rob

take a 9v to the injectors?

never heard about that can you elaborate, could all the injectors be bad at one time?? I do have a 82 CJ7 that I put a 93 Cherokee 4.0 in, can I swap the PCM/ECM? don't really want to fry my other Jeep??

doesnt make sense that all six wouldn't work unless they all got totally gunked up at once.... Im half clueless when it comes to engine swaps though so idk about the computers. but touch the terminals of the 9v with the injectors connectors, they should open up

Ok, I went ahead and took the ECM out of the cherokee and put it in my CJ7 with the 4.0, and the computer is fine, it runs my CJ7.

Also I keep coming back to the noid lights, I get no kind of light on the injectors.

I did take the fuel tank out and flush it, there was no junk what so ever, just bad fuel, I put 5 gal of fresh fuel in the tank and have fresh fuel at the Pressure test port on the fuel rail.

I am really stumped on this, the cherokee has 160,000 miles, really just broke in

Trace the wire back to the computor and test it there with the noid light then you now for sure its the computor that is bad.

Further down in the post, I did change the PCM (computer) with the one on my other jeep, the computer out of the cherokee runs fine in my other Jeep. you said trace the wire back, which wire

Just to confirm it is a fuel delivery problem get a can of starting fluid and blast it into the intake and it should fire up then as long as you are getting spark. Let me know if it starts in this manner.

The ones for the injector pulse.https://www.cherokeeforum.com/images/icons/icon14.gif

I have done this, it will run when I spray starting fluid in the intake

Rich,

Let me see if I understand what your telling me,:wacko: (sorry) you want me to trace the pulse wires back to the PCM to see if they are corroded, cut etc.

Yes thats would be a good start and hopefully your answer guy.

cps replace it

I did replace this even know I have no check engine light or codes

I wish people would stop saying to change the crankshaft position sensor everytime someon'e jeep won't start. If you have spark - The crank sensor is not your problem.

Injector pulse is controlled by the camshaft position sensor. It's in the distributor.
If your injectors aren't pulsing, it's most likely the cam sensor, the pcm, or the wiring somewhere in between. There is probably a test procedure for the cam sensor, but I don't know it. Since you've verified a functioning pcm, I'd start with the cam sensor...
Good luck