Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I have a Honda GX390 13hp engine and I was getting ready to change the oil and noticed that there is gas in the oil reservoir. What is the problem?

What type of equipment is it in/on?
Does the equipment have a manual fuel shutoff ( i believe all honda's have a fuel shutoff at the carb)
Having you been turning off the fuel when the engine is not in use?


Most common problem with any of these type carbs with the tank mounted above the float bowl, is that unless you shut off the gas to the carb you will always have the head pressure of the fuel in the tank pressing against the needle and seat in the carb.   If the needle and seat isn't PERFECT fuel will eventually get by it and overfill the fuel bowl.  The excess fuel will then pass up the main jet passage and into the intake manifold.   If the intake valve is not  the excess fuel will get by the valve and start to fill the space above the piston with gas which will eventually seep by the rings and get into your oil.

Do not under any circumstances start this engine.  Remove the spark plug, then either use the electric start or pull the engine over several times to make sure no gas is still in the combustion chamber.  Do not stick you face in front of the spark plug hole while doing this.

When you are certain there is no more gas in the combustion chamber replace the spark plug or replace if necessary.   Drain and refill  the crankcase with the correct oil, refill the fuel tank, turn on the gas and start the engine.

When you are done with you power equipment if it has a fuel shutoff make sure to use it.  If it doesn't have a fuel shutoff install one.  They are dirt cheap easy to install and will save you many headaches in the future.

In most cases the needle and seat will not be damaged.  If the fuel was really old you may have to disassemble the carb and clean it.

Carl

Carl is spot-on.

Always close the fuel valve when not using the engine. This will prevent fuel from going anywhere.

The seat valve in the carburetor could be failing. Have the carb inspected and verify the float and seat are okay.

Depending on which GX390, there is a vent (port or tube) on the carb that can get clogged, and if the fuel valve is open...

Finally, if the tank if really full, and it's left in hot, open sunlight, the tank can pressurize, and force fuel down the tube, but again, a closed valve will stop this.

-Robert@Honda

Caveat: I work for Honda, but the preceding was my opinion alone.