M37 Mystery Problem

[copperline]

Hello all. I have a bizarre M37 problem that I can not figure out. I'm hoping you smart folks might be able to point me in the right direction.

Firstly this is a 1952 M37. Mostly original but it was converted to a fire brush truck.

I have done extensive repairs to this truck. New wiring harness, sealed gas tank, flushed out all fuel lines, rebuilt the carb on and on. The truck is in great shape.

Now to the problem.

The truck was running ok (not amazing) but drivable. The truck shut down and I couldn't get it restarted. I checked the fuel and it was bright orange and cloudy. I cleaned everything out, flushed the system, and put everything back together. New gas with a bottle of HEAT to be safe. Still wont start. Wont even cough. Starter fluid does nothing. So back to the drawing board I went. Checking everything. Fuel in the carb, good spark etc etc. Nothing worked. Turns over strong and thats all she does. I checked the ignition 24v and its present, checked all 6 plugs for spark all good. Pulled the cap and checked all of that, all good. Even rotated the timing a little just incase the distributor got knocked around. Nothing does anything.

Then my daughter came to visit for the summer and the truck sat there for two months. I have not touched the truck in that time. Then three days ago i got in and just for the heck of it tried to start her up and she fully started right up. Instant too. Ran well enough that I drove her around the ranch, up and down hills, went through all the gears, and she ran great.

Brough her back into the shop for the night. Came back the next morning and nothing. Exactly like before. Turns over strong and thats it. Not even a hint of wanting to start.

I thought that maybe i was having a grounding problem so I pulled the engine grounding strap off, cleaned up everything and put the strap back on. Also re-did the battery ground just to be safe. Continuity from the chassis to the engine block is perfect.

So thats where I stand. I am clueless as to what to check next. I have a feeling its something really simple but it eludes me.

I hope someone here has a clue, because I sure don't.

Thank you all!!

[sturmtyger380]

checked all 6 plugs for spark all good

So they had bright blue spark?

Orange gas tells me there is rust in the tank. But it would not even fire on starter fluid.

I would think with spark and starter fluid it would go, but is the timing off. Can you rotate the engine to Top Dead Center and see if the rotor is pointing to the #1 cyl.

Also check to see if the wires are in the dist cap right. If they are on wrong timing will be off. I chased one of those for longer than I would like to admit.

[m-11]

If you shot starting fluid in the carb and it didn't even try to fire, you have an ignition issue. Take your distributor cap off and see if you can spin the rotor by hand. It should not move. Next look at the the coil and see if any of the wires are damaged. Removed the coil and look at the bottom of it to see if its wet. Don't touch the liquid if its present because its toxic crap. Look inside the distributor and see if there is evidence of the liquid from the coil. If the coil is leaking its time to get a new one. As Sturmtyger380 mentioned, you should have a bright blue spark.

[copperline]

These are all great suggestions.

My spark is orange/white, certainly not blue. Unfortunately i had to replace my coil with one of the aftermarket chrome ones. I have not been able to find a good replacement coil.

I can not turn the distributor by hand.
All of the wires are in the correct order
TDC points to Cyl 1

As for the orange gas, i pulled the tank and cleaned and sealed it. No more orange gas.

I think I should order a new set of plugs and a new coil. I don't really want to order another import chrome coil though.

[RMS]

Take your distributor cap off and see if you can spin the rotor by hand. It should not move.

what about the mechanical advance ? rotor should turn a bit and be smooth.

electrical problems dont cure themselves over a fortnight.

did you pull the plugs ? sounds like wet plugs. if there is gas pooling in the manifold the ether wont make it and if it does the mixture is way off. remember the throttle pump works off vacuum. full choke will fill the manifold with gas in a few seconds of cranking. I like the blip method.... cranking choke out and quickly back in 90% of the way then in and out till the good spot is found.

shat in the gas could also mess with the check valve, over filling the carb.... un till I find how a specific motor/carb wants to be treated I always crack a fitting below the douglas valve to alert me of any over fueling and ensure that im not filling the crank case with gas.

[m-11]

I grabbed this from another forum on how to test your coil.

1. Disconnect the leads to the screw-terminals of the coil after removing the distributor cap;
2. Get an test-meter and set the meter to ohms (resistance);
3. Measure the resistance between the two primary terminals (the screw terminals);
4. Readings should show almost ZERO, just a few ohms at most (usually between 1.5 to 6 Ohms.
5. If you get a higher reading, then there is an internal break in the coil windings and coil is bad;
6. Check the HT side by inserting an ordinary auto spark-plug lead in the HT outlet of the coil (connected up and installed in the distributor, but with cap removed);
7. Fit an ordinary car spark-plug into the end of the spark-plug lead.
8. Hold the spark-plug against a good clean metal part of the engine block (paint-free). Make sure you use INSULATED pliers to hold the plug against the block or your hair will curl;
9. Get a friend to flick the ignition switch to "on" and crank the engine;
10. You should get a good spark jumping the plug-gap. If not, then the HT -side of the coil is failing.
11. Test it by connecting the ohmmeter, one lead to EITHER of the primary terminals (the screw-terminals), the other lead to the secondary terminal (the high-voltage central terminal). Around 14,000 ohms is usual.The reading should be less than 20,000 ohms. Higher than this indicates an open circuit, a very low reading indicates a shorted internal winding.
12. If coil reads ok, but vehicle won't start after running, or cuts out after running, test coil immediately..... an internal-wire breakage is most likely when coil is warm/hot.

This is as good a checkout as is possible for the coil. The usual symptoms of a faulty coil are:-

1. Vehicle won't start;
2. Vehicle starts and runs fine, but won't re-start after switching engine off;
3. Vehicle comes to a complete stop and won't re-start. When an hour or so has elapsed, vehicle starts and runs fine for a while.

[just me]

Another source of red and cloudy gas is that horrible in tank filter. They are old and just dissolve in use now. Leaving you with a tank and carb full of red strings. They will plug the passages in the carb in a New York minute. (Use the stainless steel replacement.)
Chrome coil generally equals trouble. There are alternatives but they require some ingenuity and a thorough understanding of the theory behind the system.

[Explorer0863]

Do we know what was the problem? I am suspecting the chrome coil.