Small Engine Carburetor Cleaning / Repair

Only been here a week, but it’s obvious this is a very hot topic.  Must be all the snowfall out east.  Sorry, I don’t have the problem here in sunny, southern Arizona.

I may not have snow, but I do have to cut the grass and till the garden.  The equipment (engine) is all the same.

In that most of this equipment is seasonal, it tends to sit idle through the off season.  When the grass grows, spring rains come, snow falls, we get our dormant machines out, pull the cord, and swear a lot.    Won’t start!!!

Most common problem I encounter is related to fuel and carburetion. 

Gasoline, sitting in an unsealed container, whether a fuel tank or open can (even closed can if sets long enough) loses its volatility, which is the property that makes it combustible inside the engine.  Gas, having sat through the off season, gets ’stale’ and won’t explode inside the engine when the spark plug sparks.  Use fresh gas at the start of every season.

Next most common fault I find is water getting into the float bowl of the carburetor.  This can come through the air cleaner when it rains or even simply condensation.  This water settles to the bottom of the float bowl and because the inlet of the carburetor is generally at the bottom of the bowl, this water is what is being sucked up into the engine.

If your having trouble starting your equipment, and have ruled out a problem with spark, think about dropping the float bowl and checking for water.

The bowl usually hangs from the bottom of the carburetor and is retained by a single, center screw.  Remove this screw and the bowl should fall right off.  There will probably be a gasket (square, rubber ring) that seals the bowl to the carb.  This is generally reusable for a couple of changes.  Spill out the water/gas mixture, clean any debris out of the bowl and replace.  If you can’t ‘pinch off’ the fuel line, be prepared to get a gasoline manicure in the process.

Adjustments:  Most carb adjustment specs call for a starting point of one to one and a half turn off a ‘lightly’ seated screw.  After this, ‘tweak’ these adjustments by making very small, incremental changes.