Briggs & Stratton 591378 Carburetor

The Briggs & Stratton 591378 Carburetor balances the air and fuel vapor entering your lawn mower combustion chamber.

This part fixes the following issues:

• Engine stalls immediately after choke disengagement.

• Gasoline leaks from the carburetor air intake housing.

• Unstable RPM fluctuations occur while under constant load.

• Engine refuses to draw fuel from the tank.

• Excessive dark exhaust smoke indicates rich fuel mixture.

Engine Stalling After Startup

Quick Check: Monitor whether the engine dies when transitioning from full choke to normal run position.

Fix Suggestion: Replace the carburetor to clear varnish blockages inside internal fuel metering passages.

Prevention Tip: Add fuel stabilizer to fresh gas before storing the mower for winter.

Excessive Fuel Leakage

Quick Check: Check the air intake filter area for active dripping or wet gasoline accumulation.

Fix Suggestion: Install a fresh replacement carburetor to ensure internal float needle valves seal completely.

Prevention Tip: Install an inline fuel filter to prevent dirt from holding valves open.

Unstable Engine Hunting

Quick Check: Listen for rhythmic engine speed rising and falling during steady cutting operations.

Fix Suggestion: Mount a new carburetor assembly to ensure precise, uninterrupted fuel flow under load.

Prevention Tip: Clean grass clippings away from external throttle control linkages regularly.

Failure to Draw Fuel

Quick Check: Remove the air cleaner to see if fuel reaches the carburetor throat when cranking.

Fix Suggestion: Swap out the worn unit to restore proper vacuum pressure and fuel draw.

Prevention Tip: Drain unused fuel from the carburetor bowl before long storage periods.

Customer Experience: Replacing the old unit with a genuine replacement restored quick one-pull starts and eliminated annoying engine surging during weekly mowing sessions.