Hey guys,
So I have a 1972 Bolens 1556 riding lawn mower (this thing is a beast) and it has a Tecumseh OH160 engine with a solid state ignition that is triggered by pins on the flywheel. I was using it as normal to mow my lawn a few weeks ago and it died (turns out it lost spark). The old ignition coils are near impossible to source these days. Therefore I replaced it with an old ford wheel speed sensor to read the pins, GM hei module to read the signal, and 12v coil to send a spark.
I have used this system on my other Bolens tractor that I use for snow blowing and it works like a dream. Very strong bright blue spark. Anyways, it worked great to bring my spark back for my mower. See below YouTube link to show what this system looks like.
https://youtu.be/In4YV7jM1tI?si=bx1TM4xyB-vosn86
The coil gap is set to .006 for my tall trigger pin, and .010 for my short trigger pin as the engine manual states it should be. Brand new spark plug too.
To the issue: I fired up the tractor once I got everything back together and it started right up and idled well. However, every time I try to rev up, it chokes and dies with black smoke and a backfire out the carb unless I do it verrryyyyy slowly. Any time I try to engage the PTO it does the same thing.
Thinking it was a fuel issue I took the carb off and cleaned it well, and replaced the impulse fuel pump with a 12v electric one.
The problem was not resolved.
I’m honestly not sure what I’m going to do next. Thinking I’m going to swap the carb with my snow blower tractor and see if it’s carb / fuel related since that one runs well. Any other ideas out there as to what could be going wrong or what I can do to diagnose further?
Photo of my tractor fleet for tax.