Section 5 Fuel System and Governor 5.2 Fuel Filter Fuel System Tests Most engines are equipped with an in-line fuel filter. When the engine starts hard, or turns over but will not Periodically inspect the filter and replace with a start, it is possible that the problem is in the fuel genuine Kohler filter every 200 operating hours. system. To find out if the fuel system is causing the problem, perform the following tests. Troubleshooting – Fuel System Related Causes Test Conclusion 1. Check the following: a. Make sure the fuel tank contains clean, fresh, proper fuel. b. Make sure the vent in fuel tank cap is open. c. Make sure the fuel valve is open. d.
Make sure vacuum and fuel lines to fuel pump are secured and in good condition. 2. Check for fuel in the combustion chamber. a. Disconnect and ground the spark plug leads. b. Close the choke on the carburetor. c. Crank the engine several revolutions. d. Remove a spark plug and check for fuel at the tip. 2. If there is fuel at the tip of the spark plug, fuel is reaching the combustion chamber. If there is no fuel at the tip of the spark plug, check for fuel flow from the fuel tank (Test 3). 3. Check for fuel flow from the tank to the fuel pump. a. Remove the fuel line from the inlet fitting of fuel pump. b. Hold the line below the bottom of the tank.
Open the shut-off valve (if so equipped) and observe flow. 3. If fuel does flow from the line, check for faulty fuel pump (Test 4). If fuel does not flow from the line, check the fuel tank vent, fuel pickup screen, in-line filter, shut- off valve, and fuel line. Correct any observed problem and reconnect the line. 4. Check the operation of fuel pump. a. Remove the fuel line from the inlet fitting of carburetor. b. Crank the engine several times and observe flow. 4. If fuel does flow from the line, check for faulty carburetor. (Refer to the "Carburetor" portions of this section.) If fuel does not flow from the line, check for a clogged fuel line.
If the fuel line is unobstructed, check for overfilled crankcase and/or oil in pulse line. If none of the checks reveal the cause of the problem, replace the pump. Fuel Pump Operation General Pulse Fuel Pump These engines are equipped with either a mechanical, Operation and pumping action is created by or pulse style fuel pump. See Figure 5-1. alternating positive and negative pressures within the crankcase. This pressure is transmitted to the pulse pump through a rubber hose connected between the pump and the crankcase. The pumping action causes the diaphragm on the inside of the pump to pull fuel in on its own downward stroke and to push it into the carburetor on its upward stroke.
Two check valves prevent fuel from going backward through the pump.