Small engine stops after a few seconds: Common Causes & How to Fix
1Small Engine Carburetor
Most Common Solution
Repair Instructions:
The carburetor can develop cracks from engine heat and vibration. Cracks allow fuel to leak out of the carburetor body. Check over the carburetor closely looking for any cracks or leaks. Also inspect for white corrosion powder which indicates cracks. If you see the carburetor body itself leaking fuel, it likely needs full replacement. Attempting to patch cracks rarely works, as the carburetor material is too damaged. Leaking fuel is extremely hazardous. Proper installation avoids leaks and safety risks. Never operate equipment with a leaking carburetor. Cracked carburetors that leak must be replaced, as fuel leaks have disastrous consequences. Replacing a faulty carburetor restores safe fuel system operation.
How to Replace a Small Engine Carburetor
- Disconnect the spark plug wire. Remove the wire from the spark plug so the engine doesn't accidentally start when working on it.
- Drain the gas tank. Use a siphon or pump to drain the gas from the fuel tank into an approved container. This reduces fire risk.
- Remove air filter cover. Take off the air filter housing and set aside to access the carburetor.
- Detach fuel line and throttle linkage. Use pliers to disconnect the fuel line from the carburetor inlet. Unhook the governor spring and throttle cable/rod from the carburetor.
- Remove carburetor. Take off clamp screw or nuts holding carburetor to manifold. Carefully pull carburetor away from engine.
- Clean mounting surfaces. Use carburetor cleaner and rag to wipe mating surfaces on the engine block and new carburetor.
- Install new carburetor. Place new carburetor against block, aligning holes. Reinstall clamp screw or nuts to secure in place.
- Reattach fuel line and throttle linkage. Connect fuel line back to carburetor inlet fitting. Reattach governor spring and throttle cable/rod.
- Reinstall air filter housing. Put air filter cover and housing back on, securing with clamps or screws.
- Reconnect spark plug wire. Push wire back onto spark plug and tighten nut.
- Test engine. Add gas to fuel tank. Start engine and let run, adjusting carburetor components as needed.
2Small Engine Carburetor Repair Kit
Most Common Solution
Repair Instructions:
The carburetor can develop cracks from engine heat and vibration. Cracks allow fuel to leak out of the carburetor body. Check over the carburetor closely looking for any cracks or leaks. Also inspect for white corrosion powder which indicates cracks. If you see the carburetor body itself leaking fuel, it likely needs full replacement. Attempting to patch cracks rarely works, as the carburetor material is too damaged. Leaking fuel is extremely hazardous. Proper installation avoids leaks and safety risks. Never operate equipment with a leaking carburetor. Cracked carburetors that leak must be replaced, as fuel leaks have disastrous consequences. Replacing a faulty carburetor restores safe fuel system operation.
How to Replace a Small Engine Carburetor Repair Kit
- Remove air filter & carburetor. Take off air filter assembly. Detach fuel line and remove carburetor.
- Take apart carburetor. Remove bowl, gaskets, springs, needle valve and other interior components.
- Clean carburetor body. Spray all carburetor passages and channels with carburetor cleaner.
- Install new gaskets & seals. Replace gaskets, O-rings, needle valve and other seals with those from kit.
- Inspect other parts. Check floats, throttle lever, choke mechanism for wear or damage. Replace as needed.
- Reassemble carburetor. Install components in proper order and orientation per manufacturer's directions.
- Install carburetor on engine. Attach carburetor to intake manifold using new gaskets from kit. Reconnect fuel line.
- Replace air filter. Reattach air filter assembly over carburetor inlet.
- Test & tune engine. Start engine and adjust carburetor components to tune performance.
- Make sure to test at high and low RPMs, and adjust mixture settings as needed with repair kit components.
3Small Engine Fuel Cap
Most Common Solution
Repair Instructions:
As gas gets used up, pressure builds inside the tank. The gas cap has a small vent that lets air in to relieve this pressure. If the vent gets clogged with dirt or debris, air can't enter. Pressure keeps rising in the closed tank. When it gets higher than engine pressure, this makes starting hard. To check if the clogged vent is the issue, loosen the gas cap a bit before starting. If that allows the engine to run smoothly, the vent needs unclogging. Replace the whole gas cap if the vent stays blocked. A working vent brings the tank pressure down by letting air in. This equalizes it with engine pressure for easy starting. A plugged vent seals the tank, trapping pressure that resists starting.
How to Replace a Small Engine Fuel Cap
- Check for fuel leaks. Inspect area around fuel tank for any leaks or damage. Clean up any spilled gas.
- Remove old fuel cap. Turn cap counterclockwise to unscrew it from the fuel tank opening. Pull cap and gasket off.
- Clean fuel tank opening. Use a clean rag to wipe dirt or debris from opening and threads where cap screws on.
- Inspect new fuel cap. Confirm rubber gasket is in place inside the new fuel cap. Check that vent holes are clear.
- Install new fuel cap. Place new cap over fuel tank opening, lining up threads. Hand tighten cap clockwise until snug.
- Test for leaks. Add fuel to tank. Start engine and let run for several minutes, then turn off. Inspect for any leaks at the fuel cap. Tighten more if needed.
- Check venting. Make sure cap vents properly by removing it while engine is off. You should hear a hiss of pressure releasing.
- Confirm operation. Start mower and confirm fuel flows properly to the engine without starving out. Let engine run for several minutes.
- If leaks or other issues occur, recheck cap, gasket and tank opening for problems. Make sure cap is on correctly.