93mtx primes,cranks, tach responds, but won't start

Discussion in 'Gen 1 & 2 - Emergency Issues - Help & Maintenance' started by haydenm315, Oct 25, 2020.

  1. haydenm315

    haydenm315 SHO Member

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    Car has been running fine for half a year since having time to wrench during this whole covid thing. I've been driving it a few times a week since March with only 1 issue. Wife took the car out yesterday cause I needed the truck. She fired right up, and got her there. On the way back she couldn't hold it, and stopped to take a leak, in a spot a pot :bowrofl:. Car wouldn't start after that.

    We came back today thinking it could be cps, since I do have a leaking water pump. It's on my radar to do front motor maintenance. Figured it would start when cold. I had a recent incident where the car would crank, and the tach wouldn't respond. Seemed to fire off time, but started eventually after waiting it out for a little bit. Car still wouldn't fire up this morning.

    When I turn the key on, the fuel pump primes. There's still a constant hum from it after the prime. The coolant fan also immediately comes on, which I'm not sure is normal. The tach responds and moves slightly off 0.

    When I turn the key to start, the engine cranks, and the tach responds by moving up to around 500 or so. It doesn't fire and there's no indication of spark. I tried to pull KOEO codes, but was unsuccessful. My scanner says vehicle not responding. I gave the CCRM a few love taps to no avail.

    From what I've read it could be CCRM or PCM. Suggestions where to start?
     
    Last edited: Oct 25, 2020
  2. black92

    black92 SHO Member

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    Fan on when key on but engine not running is a clue the PCM has a fault. May not be the cause of not start though.
     
  3. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    I have had that symptom when the pcm and/or engine wiring was not grounded properly. I have also had it with a bad connector at the pcm. I would look for issues related to grounds.

    Are any codes showing up?
     
  4. haydenm315

    haydenm315 SHO Member

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    I've tried to scan, but get vehicle is not responding messages from my scanner. I could try the old school voltmeter count the sweeps scan. It's possible my scanner has gone bad. Been many years since I've used the one that has the old school eec-iv plug. What grounds should I look for? The big one that goes between the firewall and intake manifold support bracket is nice and tight. There's another ground hooked up at that firewall location I can trace.

    I'm not positive, but don't think the constant fuel pump buzz and coolant fan issue started until I gave the ccrm a good love tap.
     
  5. luigisho

    luigisho SHO Member

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  6. haydenm315

    haydenm315 SHO Member

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  7. luigisho

    luigisho SHO Member

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    Then we are all in agreement. Bad PCM or wiring fault. Let's pray for easy to spot wire or pcm replacement. chasing spaghetti not my idea of fun. We are seeing an increase of both issues these days.
     
  8. haydenm315

    haydenm315 SHO Member

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    I Found another thread with similar report. They ended up replacing the pcm. https://shoforum.com/index.php?threads/sho-no-start-cooling-fans-on-full-blast-possibly-ccrm.134221/ I'll regroup and check all pcm grounds tomorrow. Never cleaned a ground in the 16 years I've owned this thing, so maybe now is a good time for that. What's the blue box behind the dash on the right side. It's been dangling around for a while it seems. Should be clipped in, but wasn't.

    Hoping it's not a nightmare wire issue. It's pretty solid under there with shonut extreme mounts and the aluminum subframe bushings. No telltale rub marks on the intake. Chances of ripping a wire are slim, but I do live in the woods with all them critters. I think it was this car that had a house in the glove box at one point...
     
  9. luigisho

    luigisho SHO Member

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    blue box should be the anti lock brake module. might want to secure it. I haven't pulled one out in a long time but I thought there were bolts that held that thing stable in there
     
  10. haydenm315

    haydenm315 SHO Member

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    Last edited: Oct 27, 2020
  11. luigisho

    luigisho SHO Member

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    All the ones I pulled came out easy. The only hang up might be if the threaded connector comes loose inside the pcm housing. I've seen maybe 3 in the past several years. More than before, maybe age related? But not alot vs how many were removed and replaced.
     
  12. haydenm315

    haydenm315 SHO Member

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    I took my time and got the computer out without a problem. Pins 20,40,60 on the PCM connector to ground all ohm out to near 0. Does that mean the verdict is in on the ECU failure?

    I see a few available on rock auto for under $220.
    CARDONE 785160 {#F2DF12A650AA, F2DZ12A650AA} Remanufactured;
    BLUE STREAK ELECTRONICS EM633 {#ECC1815, F2DZ12A650AA} Remanufactured;

    Has anyone successfully repaired these things? Something easy like an electrical component that an average soldering Joe like myself can handle? I'm kid poor, so can't drop the bills on it now.

    I'm gonna take it apart and see if anything is obvious.
     
  13. luigisho

    luigisho SHO Member

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    I would poke around for a good used one.
     
  14. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    It will be a royal pain to try to repair - they are potted to avoid corrosion and vibration issues and that stuff is near impossible to get off without damaging other stuff.
     
  15. NoSlo

    NoSlo GoldMember

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    Wanna drive to Pittsburg? There's a 1994 in U-Pull-&-Pay, ECU $31

    Or as close as Millennium Auto Parts Inc. USA-MD(Baltimore) Request_Quote 410-466-9492 (call for quote) , others $50-$100 found on www.car-part.com.
     
    Last edited: Oct 28, 2020
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  16. BaySHO Performance

    BaySHO Performance SHO Member

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  17. luigisho

    luigisho SHO Member

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    Just make sure you get a manual transmission computer. X2J is newest and what i'd be looking for in a used unit.
     

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