MUTT won't start: got no spark.

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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Hypnogator
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MUTT won't start: got no spark.

Post by Hypnogator » Wed Nov 02, 2016 12:58 pm

I'm about at my wit's end. Of course, I have only half as far to go as most. :?

Last Spring, I pulled the head and replaced all the valves, reinstalled, and adjusted. My A2 ran perfectly, for, oh, a good 20-30 minutes, then sputtered and died. Tried restarting, it sputtered once, then no more. Pulled it into the garage, where it sat all Summer (too hot to work on it).

So, recently started troubleshooting. Had issues with the power into the distributor (faulty ground). Fixed that. Now getting 24.4 V into the distributor. Checked the voltage on the positive pole of the coil, getting 23.9 volts there. Checked the resistance on the coil, 6.9 ohms and 13,900 ohms, so that seems pretty much in spec. Replaced the electronic ignition system and the distributor cap. STILL GETTING NO FIRE!!!

The plugs are all almost new, and ran perfectly last Spring.

What am I missing? Appreciate your advice. You guys are lifesavers! :D
I'm afraid I've reached that stage in life where I prefer a pedantic evening at home to a bracing exchange of gunfire in the dark.


markrdje
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Re: MUTT won't start: got no spark.

Post by markrdje » Wed Nov 02, 2016 2:33 pm

how about the gas?Still good,being pumped? sounds like a fuel problem
I missed the part about no spark(sometimes when I read I skip words,sentences)
Last edited by markrdje on Wed Nov 02, 2016 4:34 pm, edited 1 time in total.
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hambone
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Re: MUTT won't start: got no spark.

Post by hambone » Wed Nov 02, 2016 3:03 pm

We just had a member on the g838 that had the same problem as you, he ordered a NOS electronic ignition from a vendor, it was sent to him in a sealed package, he installed and still no spark, I volunteered to help him out, so headed over with a NOS coil and NOS ignition. When I arrived, I looked at his NOS ignition and could tell it didn't look NOS, looked like a take out, replaced it with my NOS and it fired right up, there is a vendor out there selling t/o's as NOS. Your problem has to be coil or ignition and with the readings on the coil, I would start with the ignition. Hambone

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Re: MUTT won't start: got no spark.

Post by Hypnogator » Wed Nov 02, 2016 4:18 pm

how about the gas?Still good,being pumped? sounds like a fuel problem
Shot starting fluid into carb -- nothing. Pulled plug and held it against block while wife cranked -- no spark.
I looked at his NOS ignition and could tell it didn't look NOS, looked like a take out, replaced it with my NOS and it fired right up, there is a vendor out there selling t/o's as NOS.
I suppose it could be bad, but this wasn't NOS from a surplus dealer, it was NIB and looked it. Identical to the one I replaced it with. Doubt I installed it wrong, as it seems to be pretty much a drop-in proposition. I'm just stumped! :?
I'm afraid I've reached that stage in life where I prefer a pedantic evening at home to a bracing exchange of gunfire in the dark.

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Re: MUTT won't start: got no spark.

Post by hambone » Wed Nov 02, 2016 4:28 pm

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Rickf
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Re: MUTT won't start: got no spark.

Post by Rickf » Thu Nov 03, 2016 5:23 am

Have you checked to verify you are still getting voltage into and out of the coil? If you have a 24 volt test light put it on the negative side of the coil (green wire) while cranking and see if the light dims 4 times per revolution. That will indicate a good module. You should put an old plug wire into the coil to ground while doing this to protect the coil and you.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: MUTT won't start: got no spark.

Post by Joe Gopan » Thu Nov 03, 2016 5:39 am

Check to see that the primary wires at the coil are not in contact where they go down over the edge of the coil. Some times they get pinched between the coil and the cap and short out.
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Re: MUTT won't start: got no spark.

Post by Hypnogator » Fri Nov 11, 2016 7:51 am

Yup! Bad Coil! Tested it as Rickf suggested, got good light on + terminal, but when my wife cranked it, nothing on - terminal. So much for bench testing coils. :evil:

Ordered new coil and installed it yesterday. Took right off and ran great. 8)

FWIW, I got a coil from Quarter Ton & Military Parts https://www.quartertonparts.com/shop/el ... n-24-volt/
They claim it is US-made, from military contract over-run. It looks identical to the foreign-made crap that seems to be all we can get nowadays, but it seems to work great. :D
I'm afraid I've reached that stage in life where I prefer a pedantic evening at home to a bracing exchange of gunfire in the dark.

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Re: MUTT won't start: got no spark.

Post by Rickf » Fri Nov 11, 2016 12:05 pm

Well, that is not exactly how I explained it but if you got no light while cranking then it was a bad coil. But if the light was going on and off and it might stay off depending on where the engine stops, then that just shows the module is good and that the coil is passing voltage. Think of the ignition module as a set of points, if the engine stops turning while the points are closed then the test light on the negative side of the coil will be out since the points are closed and the circuit is grounded. If the engine stops turning while the points are open then the circuit is not grounded through the points and the test light would be on. On the positive side of the coil the light will always be on because that is the side with the hot lead coming in.
What matters is that it is running again.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone


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