Generator wont start: Common Causes & How to Fix
1Generator Spark Plug
Most Common Solution
Repair Instructions:
Check the spark plug to see if it's worn out or damaged. If the white ceramic part is cracked, or the metal part is burned or damaged, or if there's a lot of black carbon build up on the metal part, you need a new spark plug. Use a spark plug tester to check if the spark plug isn't working right. When the engine is trying to start, you should see a bright spark between the parts of the tester. If there's no spark, it means the spark plug isn't working the way it should, and you should get a new one.
How to Replace Generator Spark Plug
- Disconnect the battery. Always disconnect the negative terminal first to prevent sparks.
- Locate the spark plug. The spark plug is threaded into the engine block. Refer to the manual for exact location.
- Clean the area. Use a wire brush to clear dirt and debris around the spark plug.
- Remove the plug. Use the appropriate spark plug socket to unthread the old plug from the block.
- Inspect the plug. Check the old plug for wear and fouling. This can indicate issues.
- Gap the new plug. Use a spark plug gap tool to set the gap on the new plug to the manual spec.
- Install the new plug. Carefully thread in the new properly gapped spark plug by hand.
- Torque the plug. Tighten spark plug to specified torque in foot-pounds using a torque wrench.
- Reconnect battery. Once the new plug is securely installed, reconnect the negative battery cable.
- Test operation. Start the generator and check for proper performance.
2Generator Carburetor
Most Common Solution
Repair Instructions:
Your carburetor could be blocked. This often happens when fuel stays in the generator for a long while. As time goes by, parts of the fuel can disappear and leave a sticky, thicker material behind. This sticky material can block the carburetor and stop the engine from starting. If your carburetor is blocked, try using a carburetor cleaning product. If it still doesn't work well after cleaning, you might need to rebuild or replace the whole carburetor.
How to Replace Generator Carburetor
- Disconnect the battery. Always disconnect the negative terminal first to prevent sparks.
- Drain the fuel. Use an approved container to drain gas from the carburetor bowl and fuel tank.
- Remove air filter housing. Detach the air filter assembly to access the carburetor.
- Disconnect fuel line. Loosen the fuel line clamp and detach the line from the carburetor. Plug line to stop fuel flow.
- Remove carburetor. Take out the carburetor mounting bolts and detach the throttle linkage. Carefully remove the carburetor.
- Install new carburetor. Carefully mount the new carburetor, attaching throttle linkage and mounting bolts.
- Connect fuel line. Attach the fuel line to the carburetor inlet and tighten the clamp securely.
- Reattach air filter housing. Reinstall the air filter assembly and inspect for proper fit.
- Refill fuel. Add fresh gasoline back into the fuel tank.
- Check for leaks. Inspect the fuel line connection and seals before starting the engine.
- Reconnect battery. Reconnect the negative battery cable once all checks are complete.
3Generator Ignition Coil
Most Common Solution
Repair Instructions:
The ignition coil gives power to the spark plug when the engine is running. If the ignition coil isn't working right, the engine might not start. Before you get a new ignition coil, make sure the spark plug is working as it should. If you're sure the spark plug is okay, use a tool called an ignition coil tester to check the ignition coil. If the ignition coil isn't working right, it's time to get a new one.
How to Replace Generator Ignition Coil
- Disconnect the battery. Always disconnect the negative terminal first to prevent sparks.
- Locate the coil. The coil is mounted on or near the engine block. Refer to the manual for exact location.
- Remove coil mounting bolts. Use appropriate hand tools to detach any brackets or bolts securing the coil.
- Disconnect the wires. Label and remove the primary and secondary wires from the coil terminals.
- Install new coil. Secure the new coil in the same location with mounting bolts.
- Reconnect wires. Attach the primary and secondary wires to the corresponding terminals on the new coil.
- Inspect connections. Confirm all wiring is securely reattached and properly routed.
- Reconnect battery. Once coil is installed, reconnect the negative battery cable.
- Test operation. Start the generator and confirm normal performance.
- Secure hardware. Tighten mounting bolts to proper torque specs once operation is verified.
4Generator Recoil Starter
Common Solution
Repair Instructions:
If the generator isn't starting, the problem might be with the recoil starter assembly. This part should connect with the crankshaft to get the engine running. To check if it's working correctly, you need to take off the starter assembly.
How to Replace Generator Recoil Starter
- Disconnect the spark plug wire from the spark plug to prevent accidental starting while working on the generator.
- Remove the recoil cover on the generator by unscrewing any screws or bolts. The recoil starter is located under this cover.
- Examine the recoil starter to locate where it is mounted to the generator with bolts or screws. Make note of how the recoil is oriented so you can install the new one properly.
- Remove the mounting bolts to detach the recoil starter from the generator. Support it as you remove the last bolt so it doesn't fall.
- Install the new recoil starter using the same mounting bolts. Make sure it is oriented properly before fully tightening the bolts.
- Attach the recoil rope to the pulley on the new recoil starter if needed.
- Reinstall the recoil cover and tighten all screws and bolts securely.
- Reconnect the spark plug wire to the spark plug.
- Test the new recoil starter by pulling the rope several times to ensure smooth operation before returning the generator to service.
5Generator Start Switch
Common Solution
Repair Instructions:
If the start switch is hard to turn or only works sometimes, you should replace it. To see if the start switch isn't working right, use a tool called a multimeter to test it. When the switch is in the 'on' position, it should have an open contact. When it's in the 'off' position, it should have a closed contact.
How to Replace Generator Start Switch
- Disconnect the spark plug wire from the spark plug to prevent accidental starting.
- Disconnect the battery if the generator has an electric start function.
- Remove any screws or panels necessary to access the back of the start switch.
- Label all the wires connected to the start switch so you know where to reconnect them.
- Disconnect the wires from the start switch.
- Unscrew the mounting nuts to detach the start switch from the control panel.
- Install the new start switch using the same mounting nuts. Make sure any gaskets are properly aligned.
- Reconnect all the wires to the same terminals they were originally connected to based on your labels.
- Secure the wires with zip ties or wire clamps if necessary.
- Replace any removed screws or panels to complete the installation.
- Reconnect the spark plug wire and battery if disconnected.
- Test the new start switch by starting and stopping the generator several times.
6Generator Safety Switch
Common Solution
Repair Instructions:
To help determine if the safety switch is defective, use a multimeter to test for continuity. If there is no continuity upon testing, the safety switch will need to be replaced.
How to Replace Generator Safety Switch
- Disconnect the spark plug wire from the spark plug to prevent accidental starting.
- Disconnect the battery if the generator has an electric start.
- Remove any panels or covers necessary to access the safety switch.
- Label all the wires connected to the old safety switch so you know where to reconnect them.
- Disconnect the wires from the old safety switch.
- Unscrew the mounting nuts or bolts to detach the old safety switch.
- Install the new safety switch using the same mounting hardware. Make sure any gaskets are aligned properly.
- Reconnect all the wires to the matching terminals on the new safety switch based on your labels.
- Secure loose wires with zip ties or wire clamps as needed.
- Replace any removed panels or covers.
- Reconnect the spark plug wire and battery if disconnected.
- Test the new safety switch by starting and stopping the generator to ensure proper operation.
7Generator On-Off Switch
Common Solution
Repair Instructions:
If the On-off switch only works sometimes, you should replace it. To see if the on-off switch isn't working right, use a tool called a multimeter to test it. When the switch is in the 'on' position, it should have an open contact. When it's in the 'off' position, it should have a closed contact.
How to Replace Generator On-Off Switch
- Disconnect the spark plug wire from the spark plug to prevent accidental starting.
- Disconnect the battery if the generator has an electric start.
- Remove any panels or covers to access the back of the on/off switch.
- Label all the wires connected to the old switch so you know where to reconnect them.
- Disconnect the wires from the old on/off switch.
- Unscrew the mounting nuts to detach the old switch from the control panel.
- Install the new on/off switch using the same mounting nuts. Make sure any gaskets are properly aligned.
- Reconnect all the wires to the matching terminals on the new switch based on your labels.
- Secure any loose wires with zip ties or clamps as needed.
- Replace any removed panels or covers.
- Reconnect the spark plug wire and battery if disconnected.
- Test the new on/off switch by starting and stopping the generator several times.
8Generator Flywheel Key
Common Solution
Repair Instructions:
The ignition coil gives power to the spark plug when the engine is running. If the ignition coil isn't working right, the engine might not start. Before you get a new ignition coil, make sure the spark plug is working as it should. If you're sure the spark plug is okay, use a tool called an ignition coil tester to check the ignition coil. If the ignition coil isn't working right, it's time to get a new one.
How to Replace Generator Flywheel Key
- Disconnect the spark plug wire from the spark plug to prevent accidental starting.
- Remove any covers or panels necessary to access the flywheel.
- Use a flywheel puller to remove the flywheel from the generator shaft
- Clean the flywheel keyway on the shaft to remove any debris.
- Inspect the keyway for damage and repair if needed.
- Remove the old flywheel key - it may be sheared or cracked.
- Install the new flywheel key in the shaft keyway. Make sure it is fully seated.
- Align the flywheel key with the flywheel keyway before reinstalling the flywheel.
- Use a flywheel puller to reinstall the flywheel onto the shaft, making sure the keyway and key are properly aligned.
- Tighten the flywheel nut or bolts to the manufacturer's specified torque.
- Replace any covers or panels that were removed.
- Reconnect the spark plug wire when finished.
- Test run the generator to ensure proper operation.