97 LT40 Stalls out

[Hopkins85]

I have a 97 LT40 with original Onan 24 horse with 6000 hours.  For about a year now it has been randomly stalling out at idle and into a cut.  I'll wait about ten minutes and it will restart and run fine for days even weeks without it happening.  I put a spark tester on it and no spark.  One side of the coil lights a test light with key on and the both pulse the test light when I crank the engine. Seems odd that both sides of the coil pulse because when it starts only one side pulses? I tried an old coil from a parts engine I had that was cracked at the bottom, it started and ran for a while and then started stalling.  Any thoughts?  Thanks

[WV Sawmiller]

   A year or so back I had a problem with a jumper wire between the coils on my 25 Kohler. Both coils ran fine until you connected the jumper wire then it killed the second coil. I assume they are part of the grounding or such and without the jumper wire when you turned the switch off the engine would continue to run till it choked down from fuel starvation. I replaced the second coil and it runs fine with the jumper wire connected. I kept the second coil as a spare because I could run the mill without the jumper and live with starving the engine in an emergency if I had to.

    I am no electrician (or much of a mechanic) and have no idea what caused the problem. The jumper wire came installed from the factory/WM.

    Good luck.

[Ben Cut-wright]

One side of the coil (+)is ignition switch battery voltage and should never "pulse".  That circuit should provide current until it pops a fuse or lets the smoke out of the wire. The other terminal (-) should pulse when the engine is cranked.  Disconnect the positive wire and recheck for the pulsing.  IF...the pulsing stops the positive coil circuit may be defective/marginal, cannot supply enough current to the coil.  This test does not prove the coil is good or bad, only tests the circuit feeding the coil. 

[Hopkins85]

Okay I'll try that next time it acts up. It ran all day today.