46 Farmall M No Spark

[TractorJake]

I have a 46 Farmall M, I put the 12v conversion kit on it last weekend and got it sparking however I was unable to get it to run.

Fast forward a week, I put new points and a new condenser in it (old ones were burnt out/ lobe on points was incredibly worn). After I got these in it, I tried firing it up but got no spark. I double checked the gap and that all connections were good. I came to the conclusion that the coil was the wrong fit. It was a 12v internally resisted coil and my kit had an external resistor. So I grabbed a 6v brand new coil, tried it, and still have no spark.... once again double checked all connections but no luck. Is something either not being ground out or incorrectly ground out? I'm stumped on how I've lost spark when it had a nice spark last week....

 

[old]

I have a 46 Farmall M, I put the 12v conversion kit on it last weekend and got it sparking however I was unable to get it to run.

Fast forward a week, I put new points and a new condenser in it (old ones were burnt out/ lobe on points was incredibly worn). After I got these in it, I tried firing it up but got no spark. I double checked the gap and that all connections were good. I came to the conclusion that the coil was the wrong fit. It was a 12v internally resisted coil and my kit had an external resistor. So I grabbed a 6v brand new coil, tried it, and still have no spark.... once again double checked all connections but no luck. Is something either not being ground out or incorrectly ground out? I'm stumped on how I've lost spark when it had a nice spark last week....

Here is a simple trouble shooting test you can use. Take a wire and hook it to the ignition side of the of the battery and then touch the ignition side the coil on and off a few times. You should see a small spark when you do that and the point being closed. Next turn the engine just enough to open the points and touch the wire back to the coil. If you have spark both ways you have a short in the distributor. If no spark when the points are closed they need ot be cleaned

 

[TractorJake]

Here is a simple trouble shooting test you can use. Take a wire and hook it to the ignition side of the of the battery and then touch the ignition side the coil on and off a few times. You should see a small spark when you do that and the point being closed. Next turn the engine just enough to open the points and touch the wire back to the coil. If you have spark both ways you have a short in the distributor. If no spark when the points are closed they need ot be cleaned

Thanks for the response, I will have to try that test. I'm assuming a bad ground from the distributor. I have removed the plate and I'm cleaning all connections for it. I'm also going to clean where the distributor mounts to the engine. I have a feeling since I rotated the distributor to set timing, I've lost ground since the distributor has been painted.

 

[wore out]

I have a 46 Farmall M, I put the 12v conversion kit on it last weekend and got it sparking however I was unable to get it to run.

Fast forward a week, I put new points and a new condenser in it (old ones were burnt out/ lobe on points was incredibly worn). After I got these in it, I tried firing it up but got no spark. I double checked the gap and that all connections were good. I came to the conclusion that the coil was the wrong fit. It was a 12v internally resisted coil and my kit had an external resistor. So I grabbed a 6v brand new coil, tried it, and still have no spark... once again double checked all connections but no luck. Is something either not being ground out or incorrectly ground out? I'm stumped on how I've lost spark when it had a nice spark last week....

It is VERY likely the new breaker points have a non-conductive coating on them.

With points "open" clean them with electrical contact cleaner and allow to air dry. Then, crank the engine enough to close the breaker points and burnish them by drawing a clean white strip of cardstock through them repeatedly.

Crank the engine enough to open the points and give them another shot of electrical contact cleaner to remove any lint and debris and allow the cleaner time to evaporate before checking for spark or attempting to crank the engine.

Another tip... feeler gauge sets get used for oily jobs like setting valves, so clean the one you are going to use to set the points with electrical contact cleaner and let it dry before jamming it into the points.
.
It is said that just the oil from human skin/fingerprints on a feeler gauge is enough to contaminate a nice new set of breaker points!

 

[old]

Thanks for the response, I will have to try that test. I'm assuming a bad ground from the distributor. I have removed the plate and I'm cleaning all connections for it. I'm also going to clean where the distributor mounts to the engine. I have a feeling since I rotated the distributor to set timing, I've lost ground since the distributor has been painted.

As long as the shaft part of the distributor that goes in the engine hasn't been painted it should have a good ground.

 

[used red MN]

Hello Jake, welcome to YT! Not to embarrass you but just for information was this a running tractor before the attempt was made to convert it to 12 volts? The suggestion to play “spark doctor” with a live non-fused wire from the battery is probably not the best recommendation that can be made to a novice tractor repair man. I am sure it works well for him being experienced and all. In my opinion it would be better to acquire an automotive circuit test light for troubleshooting problems like this. Following up to the very good instructions on cleaning the points; the test light will verify your success. Connect the clip on lead of the test light to a good ground point on the engine. Often coils are mounted in a plated bracket, this is an ideal item to clip onto. The ground should be verified every time the test lead is connected. Touch the probe to the ignition side of the battery and it should light to verify the lead is grounded gOpen the distributor cap and check that the points are closed. Hold the probe on the terminal coming out of the distributor, the light should not light. Then turn the engine to open the points and this should make the test light shine. As old indicates, if you have Not power on the distributor side terminal with the points open somewhere your points circuit is ground either on the newl installed points or the terminal passing through the side of
The distributor housing. Try to complete the first part of the test with the points closed as quick as possible. If the light verified that test above hold the probe on the distributor terminal and crank the engine. This should make the test light blink of and on. If you get this point you can be assured you are about 85-90 percent assured you tractor will have spark and run.

 

[grandpa Love]

Get a cheap electric tester,see where your spark stops. Clean the points ( as much as it takes to make them spark, sometimes it takes a good cleaning)