This is a ~2013 Troy Bilt Horse tractor.

I need some advice on how to troubleshoot my mower starting. It cut out right when I was mowing, and had cut out intermittently for a few days before that. It would never actually stall, just start to kind of like I had raised up the seat and grounded the dead-man switch.

Now, I have done the following:

  • Checked the gas and the fuel line past the filter, and there's gas flowing.
  • Verified the mower turns over, and verified 2 of the safety switches:
    1 If the brake is on, it turns over. If the brake is off, it does not. I take this to mean the brake safety switch is working

    2 If the PTO is dis-engaged, it turns over. If it is engaged, it does not. I take this to mean the PTO switch is functioning

    3 Verified that the seat switch is hooked up, and it appears to work mechanically. I'm not sure that this is not the problem - maybe a short in the wire?

Mower turns over OK, it just won't start now. The first maybe 5 times I tried it sounded like it was going to start then died. Now it just turns over with no change to the noise or cadence of the motor.

What should I do to test the shorted wire? I have removed the mower cover and can see some of the wiring harness. I also have the spark plug and magneto accessible.

Any suggestions as to what to do? I can't inspect the seat switch wire 100% because it goes through the body of the mower. What's likely the problem?


  • So the starter cranks? Is the fuel filter clean? Is the air filter clean? Is the spark plug clean?
    – Tester101
    Commented May 8, 2016 at 0:04
  • Starter cranks, air filter is clean (removing it makes no difference), have fuel flow just fine. I will replace the plug tomorrow
    – mikeb
    Commented May 8, 2016 at 0:50
  • On my little lawn tractor the switch failed, when mowing it would die and backfire. That switch was not shorted but open , as a safety device it would not let the tractor run. I put a jumper in place of the switch and it started and ran fine. I was going to buy a new switch and my wife said (well can't say that here she hated having to restart every time she got off) I am not advocating defeating a safety device but it may point you to the problem.
    – Ed Beal
    Commented May 8, 2016 at 1:10
  • Did you short it at the switch, or at the engine? My problem is that if the switch wire is shorted I need to do this after the short...
    – mikeb
    Commented May 8, 2016 at 1:34

1 Answer 1


So, I found what it was. The plug was OK, and I laid it on the engine block and cranked the mower to verify a spark. It had a spark so I figured it was fuel.

I took off the air filter cover and the 2 bolts that hold the air filter housing on the carb and removed the housing. On the float bowl of the carb there was a wire coming off and going to a jumper that was not connected. The other end of the jumper went to ground. When I hooked this back up (i.e. re-connected the wire via the jumpers), it worked like new.

I have no idea what that is, maybe something that helps atomize the fuel, or a fuel pump relay?

Dunno, but it was electrical, just not a safety switch like I thought.

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