91 YJ Shutting Down. Please Help!

    OK, The first time it happened I had it towed to a friends garage and it was diagnosed with a bad ECM. I found one locally and it worked intermittently on the lift and was working when I got it back. It drove fine for about 3 days until today. It shut down on me twice and the final time it left me stranded . I towed it back to my house tonight, with the wife's Suburban. The ECM was purchased from Paradise Motors on Rt 40. I guess the ECM I purchased, that came out of a 93 YJ, wrecked, with no hood on it, sitting out in the yard, was no good. GO FIGURE! That right there should have been the writing on the wall. But I was in a time crunch and it was local. I have purchased another ECU and it will be in on Monday. This one is re-manufactured with a warranty.


    Are ECM's a common problem for the YJ's?


    Is there anything else I could be missing?


    Any feedback would be appreciated!


    Thanks, John

    There is nothing that can't be fixed if you throw enough money at it,

    Are you sure it's not just a fuse? My friend had a similar problem..blew one of those big fuses under the hood and thought it was the ecm until we put mine on his and ruled that out of the question

    Some more info....


    :help:


    If it was the fuse, it wouldn't be intermittent.
    If it was a motor grounding problem then everything wouldn't work, right? I still get lights gauges accessories etc.
    I'm getting fuel and hear the fuel pump pressurize when I turn the key on. Motor cranks over / doesn't start
    checked the fuel rail and I'm getting fuel. NO SPARK. I'll change out the coil, cap, rotor, wires, and plugs today, to rule out that stuff. It needs it anyway. If It was a bad plug/wire, it would run rough. Not sure about the coil. The ECU Does control everything including SPARK!


    :bang:


    I think I got a weather beaten ECU from a (J U N K) yard ! Hence the name. I hope this will solve the problem. I just bought a new ECU and it's on the way.

    There is nothing that can't be fixed if you throw enough money at it,

    I just replaced the plugs, wires, cap, rotor and coil on my YJ. I took the ECM out to exchange it for the one I ordered. I decided to try it one more time so i hooked it back up and tried to start it and wha woooom, she started right up. I think this confirms that it's my
    intermittent ECM. After banging it around a little and unplugging it and replugging it back in, it started.


    The real test will be tomorrow when I install the new one.

    There is nothing that can't be fixed if you throw enough money at it,

    Thanks, I did replace it after the first time it died on me, along with the junk yard ECU and a new sending unit / fuel pump. The CCS is new. I think the only thing left now is the ECU. I hope!

    There is nothing that can't be fixed if you throw enough money at it,

    I didn't but the diagnostic program at the mechanics shop ruled it out. Is there an easy check for it?

    There is nothing that can't be fixed if you throw enough money at it,

    yeah don't belive it... my scanner said nothing was wrong either but I was haven problems... let me look over my notes, I belive you can do a omes test on it... I'll check though

    Not happy with the new ECM. Runs rough! Does the new ECM take some time for it to learn the jeep? Or could it be something else?Hmmmmmmm! What's next?

    There is nothing that can't be fixed if you throw enough money at it,

    Could I call you?


    It has a rough idol and if left idling will cut off. I ran it to cub scouts with my son tonight and it cut of on me 4 times. Each time it starts back up but runs rough. When driving it just ***Click*** shuts off. I coast to a stop and start it back up again.


    P L E A S E H E L P ! I need this to get to work and I'm out of money trying to fix it.

    There is nothing that can't be fixed if you throw enough money at it,

    I found this while trying to do research on my problem.


    Is this true?



    Quote

    If you have a bad crank sensor you can check it by cranking the motor and watching the tach. If there is no movement then most likely it needs a crank sensor. If the sensor is good you will see a slight bounce in the tach.


    I tried this and got no movement at all.

    Could this be the problem?
    I think they are around 65.00 right?
    Where is it located and how hard is it to replace?


    Thanks, John

    There is nothing that can't be fixed if you throw enough money at it,

    Edited once, last by jonzjeepyj ().


    that is usually a good indication the crank sensor could be bad, but it is not a deffinante test there are a few more things that could cause that to happen but the crank sensor is by far the most common.

    I woke up early and did some more research after the advice of omegatheway. Crank sensor sounds like the problem and the motor has 133,000 miles on her. I'll pick one up on the way home today and install it and let everyone know how I made out. I found a link on replacing it. Sounds very easy to get to and replace.


    Here is the link on replacing it....
    http://www.4x4xplor.com/cps.htm


    Thanks for all your help everyone, I'll keep you posted


    John

    There is nothing that can't be fixed if you throw enough money at it,

    Thanks Chip,
    There are so many things it could be I agree. I don't have any diagnostic tools so I will go with the most likely. In your opinion, what else could it be?


    Thanks for your help, John

    There is nothing that can't be fixed if you throw enough money at it,

    The ASD(auto shut down) relay can go bad and cause all kinds of things to stop working right, but it usually is not as intermittent as you say. There could allways be a broken wire, but again less likely to be intermittent, so like you said the crank sensor it the most likely and the most common problem. Even with a scanner you wold probably never see the crank sensor problem and even if you did you couldn't verify wheather it was the sensor or a wiring problem, what you need is a scope or high end graphing volt meter to hook directly to the crank sensor to watch signal, power and ground voltages. All that said there is probably a 90% chance it is the crank sensor if your tach is not reading.

    If you need help looking at it I may be able to help you one day after or before work, let me know and Ill see what I can do.

    Quote from Chip


    There could allways be a broken wire, but again less likely to be intermittent,


    That's pretty much what mine was, wasn't it? I had a bad splice into the coil wire which caused intermittent results. A bad or broken wire could behave similarly.

    Member since 2000

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    Quote from Slimer

    That's pretty much what mine was, wasn't it? I had a bad splice into the coil wire which caused intermittent results. A bad or broken wire could behave similarly.



    Ya but what happend to yours is not that common on an unmolested harness but allways possable. On a side note have you gotten a chance to put some miles on it yet Slimer?

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