My tractor caught on fire!

[astembr]

I bought a nice looking Murray 18hp garden tractor last week. I mowed grass with it yesterday and the engine cut off once in a while.. other times it would try to die, if I jiggled the choke a little it would catch up again (with a puff of gray/brown smoke out of the exhaust).

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?

 

[Tom Arnold]

You realize of course, that all of us are just guessing as to what happened, don't you? Flames only happen when there is something to burn. So what exactly did burn? If the tractor parts themselves weren't on fire, then the obvious alternative would be dead grass plus some grease and/or oil.

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.

 

[JT]

In a lawn mower, gas line antifreeze is not a good idea. Gas line anti freeze is alchohal based, and we have a realy bad time with alchohal in fuel causing fuel problems, it softens up the plastic and rubber parts in the carb. You are better off using your second train of thought, take off the bowl and drain the "slop" out of the bowl of the carb.

 

[Tom Arnold]

If you have a carb that cannot handle GLA, then it is going to have problems with the gasolines sold today that have up to ten percent ethanols in them.

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.