flow. If the flow is still unsatisfactory, perform step b below:
b. Replace the element in the fuel filter. If the flow is still unsatisfactory, do as instructed in step c.
c. Substitute another fuel pump that is known to be in good condition and again check the fuel flow. When
changing a fuel pump, clean all of the fuel lines with compressed air and be sure all fuel line connections are
tight. Check the fuel lines for restrictions due to bends or other damage.
If the engine still does not perform satisfactorily, one or more fuel injectors may be at fault and may be checked
1. Run the engine at idle speed and cut out each injector in turn by holding the injector follower down with a
screwdriver. If a cylinder has been misfiring, there will be no noticeable difference in the sound and operation
of the engine when that particular injector has been cut out.
2. Stop the engine and remove the fuel pipe between the fuel-return manifold and the injector.
3. Hold a finger over the injector fuel outlet and crank the engine with the starter. A gush of fuel while turning
the engine indicates an ample fuel supply; otherwise, the injector filters are clogged and the injector must be
removed for service.
Figure 1. Measuring Fuel Flow