1942 - 1947 Chevrolet Shop Manual

6-45

direct proportion to the amount of gasoline used by the engine. This means that in practically all normal driving conditions the diaphragm is pulsating within a limited movement of only a few thousandths of an inch. The diaphragm movement is controlled by linkage because, when the diaphragm is in the depressed position, due to sufficient gasoline being in the carburetor, the up and down movement of the fuel pump linkage stops, and the arm spring keeps the arm in contact with the eccentric on the camshaft.

The fuel pump has a large reservoir and surge chamber. The glass filter bowl is clamped to the cover assembly, making it a simple matter to detect the presence of sediment in the fuel pump.

Disassembly

1. Remove the filter bowl, screen, top cover screws and top cover assembly.

2. Raise the edge of the diaphragm. Using a thin-bladed screwdriver, lift the spring and oil seal over the edge of the boss in the fuel pump body.

3. Unhook the diaphragm from the link by pressing down and away from the rocker arm side.

4. Remove the valve assembly retainer screws and remove the valve retainer.

5. Remove the valve assemblies and gaskets, noting that the inlet valve is assembled in the cover and that the valve opens downward, the valve spring being visible at the bottom of the valve cage. The outlet valve is assembled in the cover and this valve opens upward, the valve spring not being visible when the valve is assembled in the cover in this position.

6. Inspect the valves to make sure they are clean.

Reassembly

1. Install the oil seal to the diaphragm push rod in the following manner: Assemble the oil seal spring, upper retainer, two leather seals, and the lower retainer with the convex side out. This is extremely important in order to seal the fuel pump from any oil that might come up from the Crankcase.

2. Raise the fuel pump link with a screwdriver, Fig. 96, install the diaphragm spring and hook the diaphragm pull rod over the end of the link.


			Fig. 95-Fuel	Pump
I	Bowl	Retainer	5	Bowl Retainer Nut
2	Filter	Screen	6	Sediment Bowl
3	Inlet		7	Outlet Valve
4	Inlet	Valve	8	Outlet
		9	Diaphragm

The inlet and outlet valve assemblies are interchangeable and each assembly is a self-contained unit made up of a valve cage, a fibre valve, and a valve spring. Both valve assemblies are held in place by a valve retainer, permitting easy and speedy removal of the assemblies.

Fig. 94—Method of Assembling Fuel Pump Diaphragm to Link

3. Install the valve assemblies and paper gaskets, making sure to install the inlet valve with the spring down and the outlet valve with the spring up. The inlet valve is assembled in the