The fuel pump is bolted to the left side of the cylinder block. It is mechanically operated by an eccentric on the camshaft. A pushrod between the cam lobe and the rocker arm drives the pump.
The pump cannot be disassembled for any type of service. If testing indicates it is not within performance specifications, the pump assembly must be replaced.
The fuel pump has a rollover check valve to meet Federal Motor Vehicle Safety Standards (FMVSS). When replacement is necessary, the replacement fuel pump must meet this requirement.
REMOVAL & INSTALLATION
See Figures 1, 2, 3 and 4
- Disconnect the negative battery cable.
- Remove the gas cap to relieve any fuel pressure from the tank.
- Using a flare or pickup wrench and an open-end wrench, loosen the threaded fuel line connection(s).
- Place a rag under each fitting to catch any dripping fuel. Remove the fitting completely to separate the fuel pump from the fuel lines. Do your best to avoid bending or damaging the fuel lines(s) while you are separating them from the pump.
- Loosen fuel pump mounting bolts approximately 2 turns. Apply force with your hand to loosen fuel pump if gasket is stuck. Rotate the engine until the fuel pump cam lobe is near its low position. The tension on the fuel pump will be greatly reduced at the low cam position.
- Remove the fuel pump attaching bolts and remove the pump and gasket. Discard the old gasket and replace.
- Measure the fuel pump pushrod length. It should be 2.34 in. (61.7mm) minimum. Replace if worn or out of specification.
- Remove all fuel pump gasket material from the engine (and the fuel pump if installing the original pump).
- Install a new gasket to the pump and install the pump using the attaching bolts. Tighten the bolts alternately to 11-19 ft. lbs. (15-25 Nm).
- Install fuel lines to fuel pump. Start the threaded fitting by hand to avoid cross threading. Tighten the nuts to 15-18 ft. lbs. (20-24 Nm) using a back-up wrench to prevent damage.
- Connect the negative battery cable.
- Start engine and inspect for fuel leaks.
- Stop engine and check all fuel pump fuel line connections for fuel leaks by running a finger under the connections. Check for oil leaks at the fuel pump mounting gasket.
The fuel pump can fail in either of 2 ways: it can fail to provide a sufficient volume of gasoline under the proper pressure to the carburetor, or it can develop a leak (internal or external). An external leak will be far easier to detect than an internal leak.
To quickly check for an internal leak, remove the oil dipstick and examine the oil on it. A fuel pump with an internal leak will allow fuel to enter the oil pan. If the oil on the dipstick is very thin and smells of gas, a defective fuel pump could be the cause.
If the engine is excessively hot, allow it to cool for approximately 20-30 minutes.Capacity (Volume) Test
- Remove the carburetor air cleaner.
- Wrap a shop rag around the fuel line and slowly disconnect the fuel line. Use a suitable flare or pickup wrench on the hex of the filter to prevent damage.
- Connect a suitable rubber hose and clamp it to the fuel line.
- Place a non-breakable (1 pint minimum) container at the end of the rubber hose.
- Crank the engine 10 revolutions. If little or no fuel flows from the hose during the 10th revolution, the fuel pump is inoperative. Replace the fuel pump.
- If the fuel flow is adequate, go to the "Pressure Test''.
- Connect a pressure gauge capable of reading between 0-15 psi (0-103 kPa), to the fuel filter end of fuel line. No tee is required.
- Start engine and read pressure after 10 seconds. Pressure should read 4.5-6.5 psi (31-44 kPa) with the fuel return line closed at the fuel filter. Replace fuel pump if pressure is above or below specification.
- Disconnect the fuel pump and connect the fuel line to the filter. Use a pickup wrench on the filter and tighten the fuel line to 15-18 ft. lbs. (20-24 Nm).