Honda Small GX Engine Troubleshooting Guide

Honda Small GX Engine Troubleshooting Guide

Below are some fundamental Honda troubleshooting issues and their probable causes for the Honda GX range of engines. Keep in mind these are broad small engine troubleshooting tips. For detailed troubleshooting refer to the Honda repair manuals.

Are you having these engine Issue’s - Engine won’t start, won’t stay running, runs poorly or is hard to start.

Check the following :- 


It might sound obvious, but it has to be said. If your engine does not start, the most obvious thing to check is that it has not run out of petrol. Make sure that you are using straight unleaded petrol for a 4 stroke engine.

Also consider the age of the fuel, if it has been more than 3 months it may have gone stale. It is extremely hard to start a machine with stale fuel.


If your engine won’t start, starts but stops after a few seconds, the carburetor may be the cause. When you leave fuel in the engine for an extended period, it can clog the carburetor. After some time, parts within the fuel evaporate.

They leave a sticky substance behind that clogs up the carburetor. Clean it with carburetor cleaner and if that doesn’t work, you will have to replace or rebuild the carburetor.

Where you find it hard to start the engine, your engine may be getting too much or not enough fuel.

If your carburetor is clogged, the engine doesn’t get the fuel it needs. The engine receives too much fuel if the carburetor choke isn’t closing as it should.

Fuel Cap

A clogged carburetor is usually the culprit when the engine stops after running a few seconds or more. Another common cause is a faulty fuel cap. A faulty cap keeps the engine from starting or makes it harder to start the engine.

As the engine consumes fuel, pressure rises in the gas tank. The gas cap has a small vent that allows air to enter the gas tank and relieve pressure. If that vent becomes clogged, the pressure in the tank will rise.

When the gas tank pressure exceeds the engine pressure, the engine stalls. Loosen the gas cap before you start the engine. If the engine continues to run with the loose cap, the vent is more than likely clogged.

Spark Plug

Check the spark plug for damage or wear. You may see a cracked insulator, a burned-away or damaged electrode, or heavy carbon buildup. If so, replace the spark plug.

You can also use a spark plug tester to see if the spark plug is defective. You should see a strong spark between the tester’s terminals when the engine is cranking. If you don’t, the spark plug is defective.

Fuel Filter

A clogged fuel filter can cause engine problems. If someone leaves fuel in the engine for a long time, some of the fuel’s ingredients evaporate. The sticky stuff left behind clogs the fuel filter and interferes with engine operation.

If you find old fuel in the engine, drain it from the fuel tank. Then, replace the fuel filter.

Ignition Coil

While the engine is running, the ignition coil sends volts to the spark plug. A faulty ignition coil keeps the engine from starting. Check that the spark plug is working.

If it is, use an ignition coil tester to test the ignition coil. Replace the ignition coil if needed.

On / Off Switch

A faulty start switch will keep the engine from starting. To see if the switch is defective, use a multimeter. Test for continuity.

Also, the switch should have one open contact, which is the ‘on’ position. It will also have one closed contact in the ‘off’ position.

If you have trouble turning the switch, or if the switch only works part of the time, replace it.

Oil Alert Switch

Like the start switch, you can test with a multimeter  to see if it is defective.  Low oil can also prevent the engine to start an d this switch prevents any spark when the oil level is low.

Flywheel Key

The flywheel key is a small, metal piece. It fits in the crankshaft, where it engages with the flywheel.

If the engine suddenly stops, the flywheel key will break in half. This prevents engine damage. Replace the flywheel key before troubleshooting further.


issue i am having is with a gx200.When you turn the fuel on it runs past the outer gasaket on the air filter housing.Any advice would be apreciated thanks

andrew mcrobbie,

Gx 160 starts and runs fine till you shake the mtr. Cleaned carb. Gas runs out fine. Tried running with no air filt and with gas cap off. Runs just fine till you shake it immediately quits but starts right up


Gx120 honda engine starts easy runs on low speed and stalls when I increase the throttle. I took the carb off and cleaned but no difference


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