Watch a video about the 4300 fuel inlet circuit.

4300 Fuel InletFuel enters the fuel inlet and travels through to the needle & seat. Along with the needle & seat the 4300 has a auxiliary inlet system located to the left of the needle & seat (fuel inlet valve).

The auxiliary inlet valve also helps heat soak by purging the carburetor to fuel pump line of fuel vapor.

The amount of fuel is regulated by the pontoon float. When the fuel in the float bowl starts to empty, the float drops, which allows the needle to drop and fuel then enters the float bowl. As fuel demand gets high and the float drops enough, the auxiliary fuel valve opens allowing additional fuel in. When the float gets back to it's level point it closes the needle stopping the fuel flow.

Note: In most cases the auxiliary valve, or secondary valve is blocked off. This is due to a flooding situation the 4300 had using this valve.

The bowl vent is indicated by the blue. Without this vent, fuel would be siphoned into the engine after the engine is turned off.

Are you having trouble with flooding?

There are several reasons for this, but the needle & seat is the 1st suspect. When adjusting the float, do not put any pressure on the needle. The viton tip is easily damaged and will leak. Dirt in the needle & seat is another popular problem.

Auxiliary Fuel Inlet

4300 Fuel Inlet
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