Section 5 Fuel System and Governor Mechanical Fuel Pump The mechanical fuel pump is built into the #2 valve cover. The actuating arm of the pump extends down inside the cover and contacts one of the rocker arms. Downward movement of the rocker arm allows the pump diaphragm to flex down, drawing in fuel. As the rocker arm comes up, the fuel is forced out toward the carburetor. 3. Remove the vacuum line that connects the pump to the crankcase. 4. Install a new pump using the hex flange screws. NOTE: Make sure the orientation of the new pump is consistent with the removed pump. Internal damage may occur if installed incorrectly. 5. Connect vacuum line between the pump and crankcase. 6.
Tighten the hex flange screws to 2.3 N·m (20 in. lb.) . 7. Connect the fuel lines to the inlet and outlet fittings. 5 Mechanical Fuel Pump 1. Disconnect the fuel lines from the inlet and outlet fittings. Pulse Fuel Pump 2. Clean the area and remove the four screws securing the valve cover/pump assembly to the cylinder head. Loosen (but do not remove) the four valve cover screws on the opposite side. 3. Lift the air cleaner mounting bracket up slightly and remove the valve cover/pump assembly. Remove and discard the old gasket. 4. Rotate the engine by hand while observing the actuating rocker arm.
Stop rotating when end of the rocker arm is at the lowest point (spring is at maximum compression, and valve is open). Mechanical Fuel Pump Figure 5-1. Fuel Pump Styles. Replacing The Fuel Pump Replacement pumps are available through your source of supply. To replace the pulse pump follow these steps. Note the orientation of pump before removing. 5. Position the new gasket onto the new cover/fuel pump assembly and install onto cylinder head. Align the air cleaner mounting bracket holes with the upper two valve cover screw holes. Pulse Fuel Pump 1. Disconnect the fuel lines from the inlet and outlet fittings. 6.
Install the longer screws in the upper holes and the shorter screws in the lower holes. Finger tighten all eight valve cover mounting screws (four each side), then torque the screws to 6.2 N·m (55 in. lb.) in the sequence shown in Figure 5-2. 2. Remove the hex flange screws mounting fuel pump to support. 5.3