How to Troubleshoot a Kohler Lawn Mower Motor

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Things You'll Need

  • Bucket

  • Spark plug wrench

  • Regular screwdriver

Removing the spark plug and checking for fuel on its tip helps determine if fuel delivery is adequate.

Kohler engines are the workhorse of the lawn mower and generator industry. The first engine from Kohler dates back to the 1920s where it was part of a generator set providing power to rural communities. Since then, the engine manufacturer continues to lead in small engine technology and innovation. Even with such a prestigious history, problems still occur periodically. Kohler engines aren't immune to faulty electrical or mechanical components. Fuel delivery is among the most common issues encountered on Kohler lawn mower engines. When such a problem does happen, the primary objective is to get the engine back on-line with as little sweat and expense as possible.


Step 1

Check the obvious items before moving into the more difficult troubleshooting tasks when engine problems occur. Often, something as simple as fuel quality or level may create an engine starting or operating issue. Ensure the fuel tank has gas in it, and that it is not contaminated with dirt or water that will prevent fuel combustion.

Step 2

Troubleshoot the fuel system for symptoms that include: engine fails to start, engine will not idle and engine dies shortly after starting. Each of these can be a result of inadequate fuel delivery to the carburetor. After two or three attempted starts without success, remove the spark plug and check the tip for signs of fuel. If there is no fuel on the spark plug, a fuel restriction is occurring.


Step 3

Remove the fuel line running from the fuel tank to the inlet of the fuel pump. Hold the end of the hose over an empty bucket or catch pan and turn off the fuel shut-off valve. If no fuel flow occurs, the fuel restriction is upstream of the fuel pump. If fuel flows readily, the fuel pump is suspect.

Step 4

Reconnect the fuel line to the fuel pump inlet. On the outlet side of the fuel pump, locate the fuel line running to the carburetor. Remove the fuel line from the carburetor’s inlet and secure it over the catch pan to prevent spilling gasoline onto the ground. Turn the engine ignition key and observe the fuel line for gasoline flow. If fuel flows, the carburetor is suspect. If no fuel flows, the fuel pump is bad and requires replacement.


Excessive bubbles or cloudiness in the fuel tank is an indication of water contamination.


Always use care when working around electrical spark potential and gasonline--even with lawn mower engines.



Damon Hildebrand

Damon Hildebrand is a retired U.S. Navy veteran. He has more than 15 years within the oil and gas industry in both technical and managerial positions. Hildebrand has been a technical writer and communicator for the last four years. He is a certified specialists in lubrication and tribology, as well as a certified maintenance and reliability professional.