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Thread: Ignition issue - looking for troubleshooting help

  1. #1
    Junior Member
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    Question Ignition issue - looking for troubleshooting help

    Hello all,

    This morning I discovered that my car will not start, however it would crank just not turn over. Here are the things I have checked:
    • Inertia switch - the plunger is not in the up position.
    • I am getting power to the coil.
    • Looked for corrosion / loose connections on the two plugs for the ECU module and made sure they were tight.
    • Looked for corrosion / loose wires at the ballast connections.
    • Tried to confirm spark at the plug, but it seems like my spark plugs are seized and I don't want to force them... I'll have to sort that out separately.
    • Used a 2-wire jumper on the RPM relay between the power and fuel pump. When I did this, I could hear the fuel pump humming.
    • Used a 3-wire jumper on the RPM relay between the power, lambda system, and fuel pump. Before I did this, I was not hearing the 1-second buzzing that I typically hear when I turn the key to the run position (which I believe is the fuel system being primed). After I did this, I could hear the aforementioned buzzing except that it didn't stop on its own until I removed the jumper. That seems like a problem, yes? I found another discussion on the forum which stated that having a 3-wire jumper in this configuration should allow the car to run in normal operation... but hearing that louder buzzing (not the low hum of the fuel pump) that never stops seems like an issue.

    I did get the car to start briefly while using the 3-wire jumper in place of the RPM relay. I can't remember exactly what order I did things in - I was only leaving the jumper in place for a very short time because I was worried about what might happen if I left it in that state. At this point I think I have run down the battery too much to continue fiddling with it and I'm also not confident in what I am doing, which is why I am here. I have it on the trickle charge now as I do some more reading. Any advice would be welcome!
    Last edited by Bison; 04-30-2023 at 01:34 PM.

  2. #2
    Administrator Ron's Avatar
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    See if the coil will make spark jump to the engine block. If so you might not have an ignition problem - Give it a 1-2 second shot of starter fluid...

  3. #3
    Senior Member Rich's Avatar
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    Quote Originally Posted by Bison View Post
    ....I did get the car to start briefly while using the 3-wire jumper in place of the RPM relay. I can't remember exactly what order I did things in - I was only leaving the jumper in place for a very short time because I was worried about what might happen if I left it in that state. ...
    +1 on Ron's advice.

    Also this side note:

    The RPM relay circuit shuts off the fuel pump 1 sec after the engine stop even if the key's in the ON/RUN position. Like the inertia switch system, it's a safety circuit so it shouldn't be disabled for normal driving.

    So it's OK to leave the jumper wire in place of the RPM relay as long as you like for *troubleshooting* purposes or for use as a limp-home fix in case the RPM relay fails. (I just carry a spare one in the car)
    March '81, 5-speed, black interior

  4. #4
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    Quote Originally Posted by Ron View Post
    See if the coil will make spark jump to the engine block. If so you might not have an ignition problem - Give it a 1-2 second shot of starter fluid...
    Thanks for the response. I want to give this a shot but don't know how. Does this video accurately describe the procedure to test the coil? https://www.youtube.com/watch?v=rJYJ3KvPhhY

  5. #5
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    Quote Originally Posted by Rich View Post
    +1 on Ron's advice.

    Also this side note:

    The RPM relay circuit shuts off the fuel pump 1 sec after the engine stop even if the key's in the ON/RUN position. Like the inertia switch system, it's a safety circuit so it shouldn't be disabled for normal driving.

    So it's OK to leave the jumper wire in place of the RPM relay as long as you like for *troubleshooting* purposes or for use as a limp-home fix in case the RPM relay fails. (I just carry a spare one in the car)
    Thanks for the tip! It seems odd that I would hear the fuel system priming constantly while using the 3-wire jumper... I would expect it to hear the priming "buzzing" sound for a second. Instead, I hear the buzzing constantly until I disconnect the 3-wire jumper. I am curious if this gives some clue as to where my issue lies?

  6. #6
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by Bison View Post
    Thanks for the tip! It seems odd that I would hear the fuel system priming constantly while using the 3-wire jumper... I would expect it to hear the priming "buzzing" sound for a second. Instead, I hear the buzzing constantly until I disconnect the 3-wire jumper. I am curious if this gives some clue as to where my issue lies?
    The three wire jumper powers the fuel pump and lambda relay without the key on. So you should hear both the fuel pump running and the frequency valve buzzing all that time. With the RPM relay installed those only get powered when the engine is running or for the prime time of about one second.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  7. #7
    Administrator Ron's Avatar
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    Quote Originally Posted by Bison View Post
    Thanks for the response. I want to give this a shot but don't know how. Does this video accurately describe the procedure to test the coil? https://www.youtube.com/watch?v=rJYJ3KvPhhY
    The video is OK. But it would be easier and better to check it on the car, by removing the coil wire that goes to the cap and replace it with a long plug wire. Then see if it will deliver a spark to the engine block (ground). That way you check everything up to the coil wire...

  8. #8
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    If you got it to run (even a little) by bypassing (jumping) the RPM relay, you have spark. You also have fuel, you got it to run and you can hear the pump. My guess is a bad RPM relay or the wiring or connectors/plugs associated with it. Jumper the fuel pump so it runs continuously for testing and the motor should run. BTW this proved out the wring and inertia switch to the fuel pump so don't touch that.
    David Teitelbaum

  9. #9
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    Thanks all for the responses! I got the car running late last night after I had it sitting on the trickle charger for 10+ hours. I let it run while I was cleaning up my workspace, and as I was closing up the fuse box area the car quit. I took a closer look and I must have bumped the fuse box, and I have a very loose connection on my #1 fuse. So I'm not sure if that was the original problem or a secondary one that I caused while trying to troubleshoot my original issue, but at least she is running again. I really need to get my car in for service as I am not very good at this. Can anyone recommend someone in the Mid-Atlantic region? I used to go to Rob Grady but it seems like he closed up shop. I talked to him awhile ago and it sounded like he might be opening a shop in PA, but I haven't been able to get ahold of him since. The only other place I am aware of in my area is Tom's Garage in Milford. Has anyone here used that shop? Any others I am not aware of?

  10. #10
    Senior Member
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    Quote Originally Posted by Bison View Post
    Thanks all for the responses! I got the car running late last night after I had it sitting on the trickle charger for 10+ hours. I let it run while I was cleaning up my workspace, and as I was closing up the fuse box area the car quit. I took a closer look and I must have bumped the fuse box, and I have a very loose connection on my #1 fuse. So I'm not sure if that was the original problem or a secondary one that I caused while trying to troubleshoot my original issue, but at least she is running again. I really need to get my car in for service as I am not very good at this. Can anyone recommend someone in the Mid-Atlantic region? I used to go to Rob Grady but it seems like he closed up shop. I talked to him awhile ago and it sounded like he might be opening a shop in PA, but I haven't been able to get ahold of him since. The only other place I am aware of in my area is Tom's Garage in Milford. Has anyone here used that shop? Any others I am not aware of?
    The shop in Tuckerton, NJ where the DMA just held their Spring Event can help. Any good auto mechanic should be able to help you.
    David Teitelbaum

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