The fuel pump is a single action AC diaphragm type. All fuel pumps used on all engines are of the diaphragm type and because of the design are serviced by replacement only. No adjustments or repairs are possible.
The pump is operated by an eccentric on the camshaft. On L6 (inline) engines, the eccentric acts directly on the pump rocker arm. On V6 and V8 engines, a pushrod between the camshaft eccentric and the fuel pump operates the pump rocker arm.
Fuel pumps should always be tested on the vehicle. The larger line between the pump and tank is the suction side of the system and the smaller line, between the pump and carburetor is the pressure side. A leak in the pressure side would be apparent because of dripping fuel. A leak in the suction side is often only apparent because of a reduced volume of fuel delivered to the pressure side. However, fuel may leak out on the suction side when the engine is OFF.
- Tighten any loose line connections and look for any kinks or restrictions. Inspect rubber hoses for cracks or leaks and replace if necessary. Inspect the fuel filter for clogging and clean or replace it as necessary.
- Disconnect the fuel line at the carburetor. Disconnect the distributor-to-coil primary wire or, on HEI systems, the distributor connector. Place a container at the end of the fuel line and crank the engine a few revolutions. If little or no gasoline flows from the line, either the fuel pump is inoperative or the line is plugged. Blow through the lines with compressed air and try the test again. Reconnect the line.
- Attach a pressure gauge to the pressure side of the fuel line with a "Tee" fitting.
- Run the engine and note the reading on the gauge. Stop the engine and compare the reading with the specifications listed in the Tune-Up Specifications chart. If the pump is operating properly, the pressure will be as specified and will be constant at idle speed. If pressure varies sporadically or is too high or low, the pump should be replaced.
- Remove the pressure gauge.
REMOVAL & INSTALLATION
See Figures 1 through 11
When you connect the fuel pump outlet fitting, always use 2 wrenches to avoid damaging the pump.
- Disconnect the fuel intake and outlet lines at the pump and plug the pump intake line.
- On V6 and V8 engines, remove the upper bolt from the right front mounting boss. Insert a longer bolt ( 3 / 8 -16 in.) in this hole to hold the fuel pump pushrod.
- Remove the two pump mounting bolts and lockwashers; remove the pump and its gasket.
- If the rocker arm pushrod is to be removed from V6 or V8 engines, remove the two adapter bolts and lockwashers and remove the adapter and its gasket.
- Install the fuel pump with a new gasket reversing the removal procedure. Coat the mating surfaces with sealer.
- Connect the fuel lines and check for leaks.