Ford Ranger/Bronco II 1983-1990 Repair Guide

Mechanical Fuel Pump


The carbureted engines use a camshaft eccentric-actuated combination fuel pump located on the lower left side of the engine block.


See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the typical fuel pump mounting

  1. Disconnect the fuel inlet and outlet lines at the fuel pump. Discard the fuel inlet retaining clamp.
  3. Remove the pump retaining bolts then remove the pump assembly and gasket from the engine. Discard the gasket.
  5. If a new pump is to be installed, remove the fuel line connector fitting from the old pump and install it in the new pump (if so equipped).

To install:
  1. Remove all gasket material from the mounting pad and pump flange. Apply oil resistant sealer to both sides of a new gasket.
  3. Position the new gasket on the pump flange and hold the pump in position against the mounting pad. Make sure that the rocker arm is riding on the camshaft eccentric.
  5. Press the pump tight against the pad, install the retaining bolts and alternately torque them to 14-21 ft. lbs. Connect the fuel lines. Use a new clamp on the fuel inlet line.
  7. Operate the engine and check for leaks.


Incorrect fuel pump pressure and low volume (flow rate) are the two most likely fuel pump troubles that will affect engine performance. Low pressure will cause a lean mixture and fuel starvation at high speeds and excessive pressure will cause high fuel consumption and carburetor flooding.

To determine that the fuel pump is in satisfactory operating condition, tests for both fuel pump pressure and volume should be performed.

The tests are performed with the fuel pump installed on the engine and the engine at normal operating temperature and at idle speed.

Before the test, make sure that the replaceable fuel filter has been changed at the proper mileage interval. If in doubt, install a new filter.

Pressure Test

See Figure 2

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Fig. Fig. 2: Fuel pump volume and pressure test

  1. Remove the air cleaner assembly. Disconnect the fuel inlet line of the fuel filter at the carburetor. Use care to prevent fire, due to fuel spillage. Place an absorbent cloth under the connection before removing the line to catch any fuel that might flow out of the line.
  3. Connect a pressure gauge, a restrictor and a flexible hose between the fuel filter and the carburetor.
  5. Position the flexible hose and the restrictor so that the fuel can be discharged into a suitable, graduated container.
  7. Before taking a pressure reading, operate the engine at the specified idle rpm and vent the system into the container by opening the hose restrictor momentarily.
  9. Close the hose restrictor, allow the pressure to stabilize and note the reading.

If the pump pressure is not within 4.5-6.5 psi and the fuel lines and filter are in satisfactory condition, the pump is defective and should be replaced.

If the pump pressure is within the proper range, perform the test for fuel volume.

Volume Test
  1. Operate the engine at the specified idle rpm.
  3. Open the hose restrictor and catch the fuel in the container while observing the time it takes to pump 1 pint. It should take 30 seconds for 1 pint to be expelled. If the pump does not pump to specifications, check for proper fuel tank venting or a restriction in the fuel line leading from the fuel tank to the carburetor before replacing the fuel pump.