See Figures 1, 2, 3 and 4
The fuel pump is a single action AC diaphragm type. All fuel pumps used on inline 6's (L6), V6 and V8 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 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.
TESTING THE FUEL PUMP
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 [cf2]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
When you connect the fuel pump outlet fitting, always use 2 wrenches to avoid damaging the pump.
See Figures 5 through 12
- Install fuel line clamps on the inlet and outlet fuel lines at the fuel pump.
- Loosen the fuel pump hose clamps, slide the clamps down the fuel hoses away from the pump, then slide the hoses off of the fuel pump nipples. If no fuel line clamps were used, plug the inlet line at this time to prevent continued fuel leakage.
- Remove the two upper fuel pump mounting bolts, then pull the fuel pump off of the fuel pump mounting plate.
- In order to remove the fuel pump pushrod, or to repair an oil leak at the fuel pump mounting plate gasket, remove the two lower bolts. Remove the mounting plate from the engine block.
- At this time the fuel pump pushrod can be slid free of the engine block.
Prior to installation, perform the following:
- Clean the fuel pump mounting flange, and both sides of the mounting plate of all oil, grime and old gasket material. It is important to clean all old gasket material from these gasket surfaces to prevent later oil leaks from occurring. Use a gasket scraper or a straight-bladed razor (be careful) to scrape tenacious material off the mounting surfaces.
- If the old fuel pump is to be reused, inspect the pump arm for excessive wear or scoring; if such damage is evident, a new fuel pump should be installed.
- Inspect the pushrod ends for excessive wear and scoring. The rod should be replaced with a new one if any damage is found.
- Apply a good amount of white lithium grease to the camshaft end of the pushrod (this will help hold the pushrod in its bore during installation), then slide the pushrod up and into its bore as far as possible.
- Apply a thin coat of gasket sealer to both sides of the mounting plate gasket and position the gasket onto the inner face of the mounting plate. Install the two small bolts in the plate holes to help hold the gasket in place.
- Install the mounting plate, bolts and gasket onto the engine block together. Alternately tighten the two bolts until the plate sits flush on the engine block. Finger-tighten the two plate bolts.
- Apply a thin coat of gasket sealer to both sides of the fuel pump gasket. Install the gasket onto the fuel pump and install the two bolts through the pump and the gasket to hold the gasket in place during installation.
- Hold the fuel pump, with the gasket installed, in your left-hand, and with your right-hand, use your index finger to push the pushrod back up into its bore (by this time it has slowly slid down until it is resting against the inside face of the mounting plate). Quickly remove your right-hand and slide the fuel pump against the engine block in such a manner so that the pump arm is against the pushrod end. If the fuel pump does not sit correctly on the engine block, chances are that the pump arm did not get against the pushrod before it slid back down. This may take several tries to get it right. Do not force the fuel pump against the engine block if it resists.
- Install the upper two fuel pump mounting bolts and tighten all four bolts evenly and securely.
- Attach both fuel hoses to the fuel pump and remove the fuel hose clamps, if used. Tighten the fuel hose clamps.
- To double check if the fuel pump is correctly installed on the pushrod, or if the fuel pump functions properly, perform the fuel pump test procedure described earlier in this section.
Except V6 and Small Block V8 Engines
- Disconnect the fuel intake and outlet lines at the pump and plug the pump intake line.
- Remove the two pump mounting bolts and lockwashers; remove the pump 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.