1. Check injection pump housing pressure in the following steps:
A. Remove the housing pressure regulator from the injection pump governor cover.
B. Install a tee adaptor between the governor cover and the housing pressure regulator.
C. Connect a pressure gauge with a dial indication of 0 to 103 kPa (0 to 15 psi) to the tee adaptor.
D. Start and run the engine, observing the gauge reading (see Figure 7-70):
• If the pressure is between 55 and 83 kPa (8 and 12 psi), go to step F.
• If the pressure is more than 83 kPa (12 psi), go to step E.
E. Replace the housing pressure regulator and re-check housing pressure:
• If the pressure is between 55 and 83 kPa (8 and 12 psi), go to step F.
• If the pressure is more than 83 kPa (12 psi), check the fuel return system.
F. Remove the pressure gauge and tee adaptor.
G. Clean any fuel spillage.
H. Run the engine to check for fuel leakage.
2. Check the fuel return system for restriction in the following steps:
A. Separate the hose of the fuel return line at the fuel pick-up/sending unit.
B. Separate the hose of the fuel return line at the housing pressure regulator on the injection pump, and
connect a vacuum pump/gauge to the hose.
C. Apply vacuum to the return line and observe the gauge reading (see Figure 7-71):
• If vacuum does not build, go to step D.
• If vacuum builds, repair the return line restriction and re-check housing pressure.
D. Attach the hoses of the fuel return line at the injection pump and fuel pick-up/sending unit.
E. Clean any fuel spillage.
F. Run the engine to check for fuel leakage.
3. Check the fuel return system for air leaks, following these steps:
A. Separate the return hose at the injection pump housing pressure regulator.
B. Install a transparent hose between the housing pressure regulator and the hose of the return line.
C. Start and run the engine, observing the fuel for air bubbles (see Figure 7-72):
• If air bubbles are not present, go to step D.
• If air bubbles are present, check the fuel supply system for air leaks (if the fuel supply system checks
good, replace the injection pump and re-check the fuel return system).
D. Stop the engine.
E. Remove the transparent hose and attach the fuel return hose at the injection pump.
F. Clean any fuel spillage.
G. Run the engine to check for fuel leakage.