The fuel pump is bolted to the left rear side of the cylinder head. It is mechanically operated by an eccentric lobe on the camshaft. A pushrod between the eccentric lobe and the rocker arm drives the pump.
See Figure 1
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 in accordance with Federal Motor Vehicle Safety Standards (FMVSS). In the event of an accident in which the car rolls upside down, the valve is intended to prevent unwanted fuel spillage. When replacement of the fuel pump is necessary, the new pump must meet the same FMVSS requirement.
The fuel pump can fail in two ways: it can fail to provide a sufficient volume of gasoline under the proper pressure to the carburetor, or it can develop an internal or external leak. An external leak will be evident; not so with an internal leak. A quick check for an internal leak is to remove the oil dipstick and examine the oil on it. A fuel pump with an internal leak will leak fuel into 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 an 11 / 16 in. backup 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 (473ml) 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, proceed to the following pressure test.
- Connect a suitable pressure gauge, 0-15 psi (0-103 kPa), to the fuel filter end of the fuel line. No tee is required.
- Start the engine and read the pressure after 10 seconds. The pressure should read 4.5-6.5 psi (31-45 kPa) with the fuel return line closed at the fuel filter.
- Replace the fuel pump if the pressure is above or below specification.
- Disconnect the fuel pump and connect fuel line to fuel filter. Use a backup wrench on the filter and tighten the fuel line to 15-18 ft. lbs. (20-24 Nm).
REMOVAL & INSTALLATION
See Figure 2
- Disconnect the negative battery cable.
- Loosen the threaded fuel line connection(s) a small amount. Do not remove lines at this time.
- Loosen the mounting bolts approximately two turns. Apply force manually to loosen the fuel pump if gasket is stuck.
- Rotate the engine until the fuel pump camshaft lobe is near its low position. The tension on the fuel pump will be greatly reduced at the low camshaft position.
- Disconnect the fuel pump inlet and outlet lines.
- Unfasten the fuel pump attaching bolts and remove the pump and gasket. Discard the old gasket and replace with a new one.
- Measure the fuel pump pushrod length. It should be at least 2.36 in. (60mm) in length. Replace if it is out of specification.
- Remove all fuel pump gasket material from the engine and the fuel pump if installing the original pump.
- Install the attaching bolts into the fuel pump and install a new gasket.
- Position the fuel pump on the mounting pad. Tighten the attaching bolts alternately and evenly and tighten 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 outlet nut to 15-18 ft. lbs. (20-24 Nm).
- Start the engine and inspect for fuel leaks.
- Stop the 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.