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1991 XJ Will not start HELP!!

i was chasing down a problem that SCREAMED CPS (bellhousing)... turned out to be a fried ECU. i pleaded w/ one of the local expert members to come help me diagnose it, thats what he came up with! swapped it out and its been running sinse.

it could also be the cps WIRING...
 
WeeTodd said:
I have a new fuel pump. I checked the fuel at the rail and there is pressure 40psi when I first tuurn the key

I have over 120psi per cylinder compression

I have spark at all 6 cylinders

and I have air

I think the timing may be out but not sure how to change it or if it is even possible

so I have all the things I need to run but it does not run

I tried changing the ECU but that did not help
I also unplugged the CPS and then there was no spark and reconnected it and the spark came back.
I TDC the crank and the rotor and cap line up with #1 cylinder
I also tried quick start and that did nothing so it’s not a fuel problem cause I could smell it on the plugs when I pulled them
Click to expand...

I dont have a timming light
 
WeeTodd said:
here is a link to a video of me cranking it over the first bit you can here it start to fire on maybe one cylinder but it only did that a couple times
http://www.youtube.com/watch?v=MvD2TnRkWY8


I then disconnected teh IAC and this is the second video
http://www.youtube.com/watch?v=FRWW4K-piVA

Let me know if they dont work I can take some more videos

Thanks for all your help!!!!!!!
Click to expand...

In the first video, with IAC connected, was someone spraying ether into the intake while you were cranking?
 
sorry, im at work and cant view youtube

fuel, air, timing, compression equals start.

are the plugs fouled with gas? no spark
is the throttle plate stuck open? too much air
double checked the distributor is not out of phase? yes. i know on my 89 when i have taken the distributor out, it took a couple of times to get it clocked correctly when on the compression stroke.
did you check the gear on the bottom of the distributor for wear or wrist pin isnt sheared? out of timing
did you verify the timing chain is not stretched, broken, or jumped a tooth? out of timing
 
WeeTodd said:
NO not in the video but it does the same thing even if someone is spraying ether in
Click to expand...

Ok. You have hot blue spark, have tried ether will cranking and still won't run.

That leaves us with timing and compression. I believe your original post said about 120 psi per cylinder?

Lets do this. Pull all the plugs. Have someone help you turn the engine over until the mark on the harmonic balancer lines up with TDC AND at the same time its coming up to that mark the engine is pushing air out of the No. 1 spark plug hole. This way we have the engine's No. 1 piston at the top of the compression stroke. You will feel the air with a strong force--the only other time the piston is at TDC the exhaust valve is open so the force will be substantially less.

With the engine at TDC on No.1, pull the distributor cap and see to what cylinder the rotor is pointing.

BTW--firing order is 153624--fifteen is too young, thirty-six is too old, and twenty-four is just right! :D
 
I have checked the TDC and it lines up with the spark plug #1

I pulled the plugs after cranking and the #2 was very wet and the others were damp
put the plugs back in and un hooked the injector wires and cranked it over and it ran for a second and it sounded good like the timing is fine. so I pluged the injectors back in and cranked nothing. unpluged the injectors cranked and it ran for a second again. this is the longest I have herd it run.

What controlls the injectors?? and I guess I need to look into a NOID light right??
 
WeeTodd said:
I have checked the TDC and it lines up with the spark plug #1

I pulled the plugs after cranking and the #2 was very wet and the others were damp
put the plugs back in and un hooked the injector wires and cranked it over and it ran for a second and it sounded good like the timing is fine. so I pluged the injectors back in and cranked nothing. unpluged the injectors cranked and it ran for a second again. this is the longest I have herd it run.

What controlls the injectors?? and I guess I need to look into a NOID light right??
Click to expand...

Yes, get the NOID, most parts stores, $3.

The ECU/PCM controls the injectors, it gits input from the synch sensor (CMP/CPS) in the distributor and along with the timing input from the CPS/CKP crank sensor the ECU/PCM decides when to fire the injectors.
 
Did you remove the factory alarm box? Firing while cranking and then dying is what the factory anti-theft does. You need to make sure that module is still installed/plugged in. The hatch, and both key locks on the doors will arm/disarm it. The ECU gets a signal from the alarm to arm/disarm the jeep.
 
I would also replace the spark plugs as i once bought a set of autojunk plugs and it rendered my truck useless..took them back and bought some ac delco and whammo she runs again...
 
sounds to me like its flooding. If it starts for a second with the injectors unplugged then it is an excessive fuel problem. Pull the IAC out and make sure the passageways are clear. If it was running fine and then stopped as the guy you got it from said it was then the problem is not likely to be an out of phase distributor. It is possible the IAC is stuck closed. Possibly a bad fuel pressure regulator too, do you have a fuel pressure gauge? also pull the vacuum line off of the regulator and kick the key on, make sure fuel is not leaking through the diaphram and going directly into the engine. If you have gas at the vacuum line then the regulator is toast.
 
I have new plugs in Bosh platinum pluss

it still has the factory alarm in it I found that out when I put the new batt in and the light started flashing but I unlocked the drivers door and the light stopped flashing.

I pulled out the IAC last night and cleaned it. I slid back the black collar and cleaned inside too. is the rounded end supposed to slide or move at all mine does not move?? is there any way to check it??

I do have a fule presure guage I will take some reading and post them
 
WeeTodd said:
I have new plugs in Bosh platinum pluss

it still has the factory alarm in it I found that out when I put the new batt in and the light started flashing but I unlocked the drivers door and the light stopped flashing.

I pulled out the IAC last night and cleaned it. I slid back the black collar and cleaned inside too. is the rounded end supposed to slide or move at all mine does not move?? is there any way to check it??

I do have a fule presure guage I will take some reading and post them
Click to expand...

The IAC is a stepper motor, and to the best of my knowledge it can be "exercised" using either the proprietary DRB tester or another dealer-only tool.
 
I have never used a NOID light but by the looks of it seams like the injector signals are good I connected it to all the injecotrs and it flashed so I conected it back on #1 and connected the park plug tested and took the following video the NOID light is on the right and the light on the left is the spark plug tester the light for it does not always show up on the camera but it was fireing after every NOID flash
http://www.youtube.com/watch?v=t5soQVw-xJ4

I also tried to connect the IAC test light and it did nothing and well not sure what it was supposed to do the kit said it was (GM 1987) here is a picture can any one tell me what it was supposed to do?? I know I know they are bad pictures ha ha but you get the idea
http://weeweetodd.googlepages.com/IMG_7696.JPG
http://weeweetodd.googlepages.com/IMG_7697.JPG

I also removed the vac line on the fule regulator and it was dry even with the key on

I am trying to get my fuel presure guage to work but it does not seam to push the little pin in on the fule rail so when I screw it on it wont read preasure


Hey Thanks for all the help I sure would be lost with out you!!
 
Im pretty sure your injectors are firing because it is flooding. The IAC should not move by hand as it is a threaded rod connected to a stepper motor, but you can plug it in and turn the key on sometimes it will move then. If you have another one to swap out try that. Im not sure on testing it with a test light in any way. Also, if you have a multimeter you should check your coolant temp sensor and also the intake air temperature sensor. Somewhere on this site there are the resistance tolerances for both of those sensors. Either one of those could cause it to flood, as could the MAP sensor. Find a factory service manual or a haynes manual and follow the test procedures for all of those sensors. After thinking about it I am not so sure that the IAC would be the problem as it sounds to me like you have an excess of fuel instead of a lack of air causing the flooding, as evidenced by the fact that it will run with the injectors unplugged until it runs out of fuel in the cylinders. Go through those sensor tests and report back young grasshopper......
 
I am stumped I have looked at every thing anyone has said on this thread and also the one I have going on JeepKings and nothing seams to work I have a friend of a friend that had a shop so I will take it to him and get him to scan it and see what he can come up with I will keep you all posted
 
this will sound odd but lets try it anyway. Have a friend help you. First, locate your fuel pump relay. Try to start the jeep as normal, to get it flooded. Then, pull the fuel pump relay. Try to start the jeep. If it is flooding, when the fuel burns down it should start for a second like it does when the injectors are unplugged. As soon as it starts, have your friend plug the fuel pump relay back in. See if it stays running.
 
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