371 project

[Tonka Toy]

Hi all, Really after some help. Have just got a 371 which was running when I got it on Saturday but went to unload it today and it wouldn't run, to keep it running I had to wire the starter to live and keep it like it. As soon as the live wire was disconnected the engine would die, as soon as it was re coonected the engine would keep running. Think I need to re-wire it but trying to find a wiring diagram and have come up blank so any help would be great, Thanks Jon

 

[SkidRoe]

That doesn't sound right. Does it still have the original engine in it? It should be a 14hp Koehler single cylinder.
Like most small engines, the ignition system is a self contained magneto-type system, generating it's own power. To kill the ignition, the ignition switch shorts it to ground when switched to the off position.
Does the wiring look like it has been missed with? The wiring on these machines is pretty simple, so if you have to re-wire, it is not the end of the world.
Cheers - SR

 

[Tonka Toy]

That doesn't sound right. Does it still have the original engine in it? It should be a 14hp Koehler single cylinder.
Like most small engines, the ignition system is a self contained magneto-type system, generating it's own power. To kill the ignition, the ignition switch shorts it to ground when switched to the off position.
Does the wiring look like it has been missed with? The wiring on these machines is pretty simple, so if you have to re-wire, it is not the end of the world.
Cheers - SR

Its weird I know, the wiring looks like the original, with only a flashing amber light added on top. It was running ok, then it wouldn't turn the started, so used a jump cable to test the starter, which then fired the engine into life. It was running fine for a few minutes without the lead on the starter, then died, so thinking something has broken down. Its still got the original Koehler engine in it. When key is turned off the engine dies as normal. Can't get my head around why the starter would have to be live to keep it running, not the best with electrics anyway but when the guy I get to look at my stuff ran his meter over it he was stumped as well. Thanks Jon

 

[SkidRoe]

Its weird I know, the wiring looks like the original, with only a flashing amber light added on top. It was running ok, then it wouldn't turn the started, so used a jump cable to test the starter, which then fired the engine into life. It was running fine for a few minutes without the lead on the starter, then died, so thinking something has broken down. Its still got the original Koehler engine in it. When key is turned off the engine dies as normal. Can't get my head around why the starter would have to be live to keep it running, not the best with electrics anyway but when the guy I get to look at my stuff ran his meter over it he was stumped as well. Thanks Jon

It almost puts me in mind of older cars with ballast resistors to the coil, and how they would bypass the resistor for starting to compensate for the drop in battery voltage while cranking. If the resistor went bad, the ignition would only get power while the starter was energized. But it does not sound like your starter is engaged, from what you describe.
The only other thing I can think of is that the generator part of the magneto is failing, and is relying on battery voltage to power the ignition circuit. By rights, there should not be a connection between the magneto generator and the battery, unless someone has jumpered it.
Just a shot in the dark - SR

 

[Tonka Toy]

It almost puts me in mind of older cars with ballast resistors to the coil, and how they would bypass the resistor for starting to compensate for the drop in battery voltage while cranking. If the resistor went bad, the ignition would only get power while the starter was energized. But it does not sound like your starter is engaged, from what you describe.
The only other thing I can think of is that the generator part of the magneto is failing, and is relying on battery voltage to power the ignition circuit. By rights, there should not be a connection between the magneto generator and the battery, unless someone has jumpered it.
Just a shot in the dark - SR

Thanks SR, Was thinking something along the same lines, but think I may have gotten to the bottom of it by accident, appears the positive wire had been replaced badly, resulting not enough power through after a crank or two, the wire heats up and terminal on battery gets hot. Going to fit the right wire tomorrow with new terminals and see how it goes, Stay tuned for more fun and games Jon

 

[SkidRoe]

Thanks SR, Was thinking something along the same lines, but think I may have gotten to the bottom of it by accident, appears the positive wire had been replaced badly, resulting not enough power through after a crank or two, the wire heats up and terminal on battery gets hot. Going to fit the right wire tomorrow with new terminals and see how it goes, Stay tuned for more fun and games Jon

Well, that sounds promising. Hope that fixes it!
Cheers - SR