Key Switch and Coil Fire Problem

[RTR]

I’m curious as to what causes a problem I am having with a Massey Ferguson 135 gas tractor. I’ve also had the same problem with a Farmall Cub and a Farmall 140 tractor ......all of which are key start systems. When starting the tractor and turning over the starter with the key switch, The switch is not letting fire/battery power to the coil. When the key/starter is released, it allows fire to the coil then. Basically when the key is on the “on” position you have power to the coil but in the momentary start position it doesn’t have power.

Is this a simple wiring issue I have made a mistake at, or does this mean the key switch is bad?

 

[Steve@Advance]

Thought we just went over this subject?
Key Switch

 

[used red MN]

This appears to be a duplicate post, I don’t know if it is caused by the YT server change issue or if rtr is trying to give us a spin.
1st go round

 

[Janicholson]

yup we did, and there were many answers. Jim

 

[old]

Could be a wiring problem or a starter problem. Try hot wiring it and see if the problem goes away. Run a wire from the ignition side of the battery to the ignition side of the starter and try to start it. If it fires up like it should you have a wiring problem if it doesn't then you have a starter pulling to many amps

 

[Janicholson]

Coil, not starter? I do that too. Jim

 

[David G]

I have also seen this issue show up with low battery or bad cables, the voltage droops so much during cranking that it starves the coil.

 

[old]

A starter going bad will cause an engine to only start as you let off on the key from start to run