Lawn Tractor won't start after being turned off ?

brin · Nov 15, 2009

I have a 20 HP Murray Lawn Tractor and lately in has backfired when I shut it down and then will not start for a long time after shutting it down. It runs fine up until the shut down and then won't start again. I have checked the air cleaner and it has clean gas. I did not go into the carb since it ran fine and has been running fine. I do the service on my tractors but his has me baffled..I am wondering if it could be the fuel filter...but since it ran fine I kinda doubt that. Any thoughts will be appreciated. Thanks

Willl · Nov 15, 2009

Any spark ?

Will it try to run with a shot of starting fluid ?

beenthere · Nov 16, 2009

Try to run down why it is backfiring, and you may find out why it is not starting.

Checked compression? Right after back firing, and then a "long time" later. This may give you a clue as to rings or valves.

zzvyb6 · Nov 16, 2009

I have a few motors that have been doing the same thing (Honda GS160 on a leaf vac and Yamaha 250 atv). I've associated it with using 15% ethanol fuel. Put a new spark plug in them and they run just fine after that. Go figure....

MikeD74T · Nov 16, 2009

Does your engine have a fuel shutoff solenoid (which is supposed to eliminate backfire on shutdown)?
May also be an exhaust valve adjustment issue, ie lengthen when heated & don't seal enough to allow restart untill cooled. MikeD74T

jinman · Nov 16, 2009

Do you smell gasoline when trying to restart? I'd sure pull a spark plug to see if it is wet as zzvyb6 suggested. Sure sounds like a flooded engine to me. The backfire you are hearing might be because of a flood of fuel on shutdown. It might even indicate that your float valve is not seating properly, especially if you don't have a fuel cutoff solenoid as MikeD74T suggested.

skent · Nov 18, 2009

I have a B&S 14 HP twin, does the same thing after running for a while. I lose the spark whenever the magnito gets hot. It won't happen when it's running, since the air goes past the magnito before cooling the cylinders, but if I shut it off when the engine is HOT, the heat from the cylinders effects the mag and no-spark for 30 or 40 minutes.