My tractor caught on fire!

By the time I finished the front yard it wasn't running well at all. It backfired loudly once shortly before I stopped. So I parked and started to take off the deck to go to the back yard (through a little gate). That's when I saw FLAMES under the hood!

Of course I panicked & ran to the garden hose and doused the engine for several minutes. I knew enough that water won't put out a fuel fire, but thankfully no fuel caught on.. it looked like a fuel hose burned a little, and a spark plug wire above that.

I checked the oil and it is fine. After cooling everything down I started it just for a brief second - it started right up and ran smoothly.

So now I have to find out what happened to cause it to spark flame like it did.

Any suggestions?

Portable fuel containers are notorious for introducing moisture into the fuel tanks of outdoor power equipment. It only takes a few drops of water to cause an engine to stutter and run badly. Backfiring is a symptom of unburnt fuel entering a hot muffler and then being ignited by glowing carbon inside the muffler. The flame emitting from the muffler could have ignited a bit of dead grass and that tiny fire found even more dead grass or other combustible material.

Gas line anti-freeze in the fuel tank will get rid of any remaining water. Removing the float bowl on the carb very carefully to see what is lurking in the bottom of it might help shed some light on the issue. You may have to hold a small clean container under the bowl as you are removing it, in order to gather up any liquids that will seep out the second you loosen the screw holding the bowl on.

Draining and cleaning the float bowl only addresses what got into the carb. It doesn't look after the root cause, which is water in the fuel tank that got there one of two ways. Either by being directly introduced into the tank from the outside or by warm, moist air condensing on the top and sides of a partially filled gas tank.