Help with no spark

Discussion in 'General IH Tech' started by rexdropssticks, Feb 15, 2020.


  1. rexdropssticks

    rexdropssticks Farmall Cub

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    Hi everyone, I'm new to here because I am at a dead end with my 78 scout plow vehicle. It will not start ,no spark, I have thrown all the obvious parts at it, New cap, rotor, plugs, pertonix ignition replacement ,all to no avail. It has the prestolite electronic distributor and no gold box on the firewall or any where else. There is a silver box on the firewall with a little what looks like vacuum unit attached but there's no hoses hooked to It now. It appears to be oil filled as it is leaking something. What is this and where could I get one? I have tested everything else and suspect this must be the culprit? Any suggestions? Thank you for your time
     

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  2. bobn

    bobn Binder Driver

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    I have no experience with the pertronix, but if that truck was mine a point distributor would in in it in short order. even if I jury rigged a toggle switch and a ballast resistor to power it up. jmho, bobn
     
  3. Dana Strong

    Dana Strong Lives in an IH Dealership

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    I don't know that system either but was unsure if you were getting no spark from the coil, or just not getting it at the correct plugs.
    Also, did this problem start on its own or after doing some work on the vehicle?

    I seem to recall that there can be problems with some Pertronics systems; which one do you have? Somebody who knows them will want to know more such details
     
  4. mallen

    mallen Y-Block King

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    Stop throwing random parts at it and start diagnosing what the fault is or you will just waste more money. Lets start at the beginning. Even if you have done these things before do them again, because you could have gotten a defective part or caused another problem when replacing things. First,eado take the center , coil lead off at the distributor but leave it connected to the coil. Put the electrode near a metal part of the engine or body. Perhaps a quarter or an eight of an inch away, but not touching. And away from the fuel lines and carburetor. Have a friend crank it and see if you get spark.
    Come back and tell me what the result was and I'll give you the next step.

    Even if you already did it, do it again. If you follow my instructions I can most likely get you running.
     
    Last edited: Feb 15, 2020
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  5. scoutboy74

    scoutboy74 Lives in an IH Dealership

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    That device on the firewall is a deceleration module. Part of the original emissions system. It has nothing to do with the ignition system.
     
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  6. rexdropssticks

    rexdropssticks Farmall Cub

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    Thank you guys!, I will work at again this morning and get back with results
     
  7. rexdropssticks

    rexdropssticks Farmall Cub

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    Mallen, I did as you said ,only I put a spark plug in the lead and there is no spark
     
  8. rexdropssticks

    rexdropssticks Farmall Cub

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    Here are a couple of pics of the distributor
     

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  9. rexdropssticks

    rexdropssticks Farmall Cub

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    If I could find a points distributor that I didn't have to take a loan out to buy I would switch it out. After all it is just my plow vehicle and is not road worthy by any means
     
  10. mallen

    mallen Y-Block King

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    Was the threaded part in contact with the metal body or engine? If so, the that will work very well, and you have verified that there is a problem upstream of that point as the coil is not producing spark. This could be any number of things, so let's continue.

    An important point to remember is, don't crank for more than 15-20 seconds at a time or you can damage your starter and don't leave the key on more than 30 seconds Or you can damage the ignition module. Let it cool down a minute between attempts to start it.


    Next, you need a volt meter. If you don't have one, go to harbor freight and get that really bad quality cheap one for something like 5 dollars. It will do the job. (A nicer one will work too, but you dont have to spend the cash unless you want a nice one. If you already have one, then your good to go.

    Now set the volt meter for DC voltage put the black lead on the negative battery terminal and the red lead on the positive coil terminal.
    What do you get?

    Now have your friend turn the key on. What voltage does it read?

    Now have your freind try to start it. What voltage do you read.
     
  11. scoutboy74

    scoutboy74 Lives in an IH Dealership

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    Looks like a standard Prestolite pickup module in the dizz. You mentioned a Pertronics in your initial post? What am I missing?
     
  12. rexdropssticks

    rexdropssticks Farmall Cub

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    Key off reads 0.02, key on reads 12.45, starting reads 9.45
     
  13. rexdropssticks

    rexdropssticks Farmall Cub

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    Yes, I bought the petronix replacement but the last (mechanic) I had here burnt it up by hooking it up wrong
     
  14. mallen

    mallen Y-Block King

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    Excellent. Next thing to do is to disconnect the NEGATIVE wire from the coil, then take a piece of wire. Connect it to the negative battery cable or a bare metal spot on the frame or engine. Touch the wire to the negative terminal of the coil for a second or two. When you disconnect it, do you get a spark.
     
  15. mallen

    mallen Y-Block King

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    Now for some more questions. Tell me everything that happened, sparing no detail from the last time it ran until right now. Everything you changed replaced etc. And everyone that touched it.In order
     
  16. rexdropssticks

    rexdropssticks Farmall Cub

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    I went to start it one snowy day and it started and stalled restarted and stalled and would not start again ,so I figured I had it flooded by now so I quit trying .It was going to warm up in the next several days and melt the snow so the hell with it. During one of those warmer days I decided to see if it would start and it did, started right up like it was new. I let it run for a bit and shut it off. Started it again , let it run for a minute and shut it off. That must have been what happened, I had flooded it before because it's fine now I guess. Next time we got snow I went out to plow and it would not start and has not since. I pushed it it the garage with the tractor and it's been there for 3 weeks. I have had 3 mechanics look at it and they have had no luck. Now when I first got the petronix I booked it up per there instructions but it still no start. Then the mechanic before the last mechanic was trying something and fried it. So there went a hundred bucks down the toilet. He then put the original prestolite module back in and said he was sorry and left. Next mechanic ttys and he's telling me that module is bad . There is no evidence looking at it that says it is bad, ie, burn marks, discoloration. And that's where I'm at
     
  17. mallen

    mallen Y-Block King

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    When exactly did you buy the prestolite. You might contact them if it's not been too long and see if it can be exchanged. Clearly these were not REAL mechanics. This stuff is not rocket science. We should be able to help you get up and running. Let me know when you have done the test I described and whether you get a spark.
     
    Last edited: Feb 17, 2020
  18. rexdropssticks

    rexdropssticks Farmall Cub

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    I assume you mean the pertronix as the prestolite was in the scout when I bought it? I bought the pertronix a week or so ago but I doubt they will stand behind something that wasn't there fault. Any way you didn't specify key on or off so key off no spark key on he's there is a spark
     
  19. mallen

    mallen Y-Block King

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    All we know is it doesn't work and never did and some idiot mechanic THINKS he hooked it up wrong.
     
  20. mallen

    mallen Y-Block King

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    Did you try that last test yet?
     

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