A fuel pump is used when the fuel tank is mounted lower than the carburetor and cannot rely on gravity to carry fuel through the fuel line. Briggs & Stratton fuel pumps have either a plastic or a metal body and develop pressure using the vacuum in the crankcase, which is created by the motion of the piston. A fitting on the crankcase cover or the dipstick tube draws the pressure to pump fuel.
The fuel pump may be mounted on the carburetor, near the fuel tank or between the tank and carburetor.
Exploded View Fuel Pump Image
Fuel Pump Operation
Mukuni Square Fuel Pump (metal)
Dual Inlet/Single Outlet Rectangle Fuel Pump
Round Fuel Pump
Spring Valve Carburetor Mounted Fuel Pump
Dual Inlet/Single Outlet Square Fuel Pump
Freezing Fuel Pump Vacuum Line FAQ
Inspecting The Pump
Turn off the fuel valve (if equipped) at the base of the fuel tank where the fuel line is attached. If there is no fuel valve, stop the flow of fuel using a fuel line clamp.
Loosen the mounting screws and remove the pump from the mounting bracket or carburetor (image A).
Check for hairline cracks and other damage to the external surfaces of the pump. If the pump is damaged and has a metal body, discard the pump and install a replacement pump from the engine manufacturer (image B).
Servicing The Pump
In some cases, a plastic-body pump may be serviced using a repair kit listed in the engine's Illustrated Parts List. A damaged metal-body pump must be replaced.
With the fuel valve closed or the line clamped, remove the mounting screws. Then, disconnect the fuel hoses using needle nose pliers to loosen the clips. Remove the screws and disassemble the pump.
Inspect the body for cracks or other damage. Soak metal parts in all-purpose parts cleaner. The pump body may be soaked for up to 15 minutes (image C).
Check the hoses for cracks, softening or hardening, and replace any faulty parts. Discard old gaskets, diaphragms and springs, and replace them with parts from an original manufacturer's repair kit
Reinstalling The Pump
Place the diaphragm spring and then the cup over the center of the pump chamber. Also insert a valve spring.
Install the diaphragm, gasket and cover and attach with pump screws. Tighten the screws to 10 to 15 inch lbs., using a torque wrench.
Attach the pump to the carburetor or mounting bracket, using the pump mounting screws.
NOTE: Please read and abide by any applicable Safety Information (PDF) before performing any engine work. This information is not meant to take the place of work performed by a Briggs & Stratton Authorized Dealer. Terms and Conditions apply to all of our information provided on this website. Always be sure to read and understand your engine Operator's Manual.