GM Firebird 1982-1992 Repair Guide

Mechanical Fuel Pump


All fuel pumps used on carbureted V6 and V8 engines are of the diaphragm type and are serviced by replacement only. No adjustments or repairs are possible. The fuel pump is mounted on the left front (V6) and right front (V8) of the engine.

The fuel pumps are also equipped with vapor return lines for purposes of emission control and to reduce vapor lock. All pumps are operated by an eccentric on the camshaft. On V6 and V8 engines, a pushrod between the camshaft eccentric and the fuel pump operates the pump.


See Figures 1, 2 and 3

When disconnecting the fuel pump outlet fitting, always use two wrenches to avoid twisting the line.

  1. Disconnect the fuel intake and outlet lines at the pump, then plug the pump intake line.
  3. Remove the two pump mounting bolts and lockwashers; remove the pump and its gasket.
  5. If the pump pushrod is to be removed from the V8, remove the two adapter bolts and lockwashers, then remove the adapter and its gasket.
  7. Install the fuel pump with a new gasket reversing the removal procedure. Coat the mating surfaces with sealer.
  9. Connect the fuel lines and check for leaks.

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Fig. Fig. 1: Most fuel pumps are more easily accessed from underneath the car

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Fig. Fig. 2: Removing the fuel pump attaching bolts

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Fig. Fig. 3: Be careful not to spill fuel when removing the pump from the engine


To determine if the pump is in good condition, tests for both volume and pressure should be performed. The tests are made with the pump installed, the engine at normal operating temperature and operating at idle speed. Never replace a fuel pump without first performing these simple tests.

Ensure the fuel filter has been changed at the specified interval. If in doubt, install a new filter first. Always check for broken or deteriorated fuel hoses. If a line has a crack or split, the pump may be operating properly, but the pump will only draw air, not fuel.

Pressure Test
  1. Disconnect the fuel line at the carburetor, then connect a fuel pump pressure gauge. Ensure the carburetor float bowl has a sufficient amount of gasoline.
  3. Start the engine and check the pressure with the engine at idle. If the pump has a vapor return hose, squeeze it off so that an accurate reading can be obtained. Pressure should be 5 1 / 2 -6 1 / 2 psi.
  5. If the pressure is incorrect, replace the pump. If it is within specifications, go on to the volume test.

Volume Test

  1. Disconnect the pressure gauge. Run the fuel line into a graduated container.
  3. Run the engine at idle until one pint of gasoline has been pumped. One pint should be delivered in 30 seconds or less. There is normally enough fuel in the carburetor float bowl to perform this test, but refill it if necessary.
  5. If the delivery rate is below the minimum, check the lines for restrictions or leaks, then replace the pump.