Walk Behind Lawn Mowers

Could be fuel delivery problem. Remove the spark plug, add a little fuel into the cylinder, reinstall the plug and plug wire. Now see if the engine will at least try to start. If it does then the fuel system and carburetor need checking; otherwise, you have an ignition system problem.

Here is a list tests you can do for fuel delivery related problems.

FUEL SYSTEM TESTS

When engine starts hard, or turns over but will not start, fuel system might be causing problems. Test fuel system by
performing following tests.

1. Check for fuel in combustion chamber.
a. Disconnect and ground spark plug lead.
b. Close choke on carburetor.
c. Crank engine several times.
d. Remove spark plug and check for fuel at tip.

2. Check for fuel fl ow from tank to carburetor.
a. Remove fuel line from inlet fitting of carburetor.
b. Use an approved fuel container to catch fuel, and
hold line below bottom of tank to observe fuel
flow.

3. Check operation of fuel shut-off valve.
a. Remove fuel sediment bowl under inlet fitting of
carburetor.
b. Turn fuel shut-off valve ON and OFF and observe
operation.

Condition Conclusion

Fuel at tip of spark plug. Fuel is reaching combustion chamber.

No fuel at tip of spark plug. Check fuel flow from fuel tank (step 2).

Fuel flows from fuel line. Check operation of fuel shut-off valve (step 3).

No fuel flow from fuel line. Check fuel tank vent, in-line filter threaded into tank, and
fuel line. Correct any observed problem and reconnect line.

Fuel flows from valve. Check for dirt and water in sediment bowl and screen.
Clean bowl and screen as needed. Check for faulty carburetor, refer to Carburetor.

No fuel flows from valve. Check for a restriction in fuel shut-off valve or inlet elbow.