Download THE 6.2 LITER DIESEL ENGINE

7. Diagnosis
Procedure 3.
Measuring Housing Pressure and Transfer Pressure
STEP 1 CHECKING HOUSING PRESSURE:
Remove the return line connector from the top of the pump (both the blackened and brass fittings).
Examine the lower end of the regulator fitting where the glass ball seats for evidence of debris. If present,
blow through the fitting w ith compressed air to elim inate the debris or replace the fitting.
Before reinstalling the fittin gs to the cover, turn the ignition key to the “ O N” position and connect a
jum per wire between the electric shut off solenoid term inal and the H.P.C.A. terminal. Make and break the
connection to the H.RC.A. term inal and observe the H.P.C.A. solenoid plunger through the return fitting
opening. It should move up and down as the current is applied and removed. If it does not function, repair
or replace the solenoid as necessary.
STEP 2 MEASURE THE VOLTAGE AVAILABLE AT THE H.P.C.A. TERMINAL:
A. When the engine is cold < 9 5 °F, there should be 9 volts m inim um at the H.P.C.A. terminal. If voltage is
low check battery and charging system condition. If there is no voltage at terminal, check operation of
temperature sensor located on right rear head. (See chassis service manual).
B. Install housing pressure gage adapter as shown using gage “ D” or J34151. Reinstall return line
connector and fuel return line, then connect pressure gage.
C. Start the engine, the housing pressure should be 8-12 PSI, WHH no more than 2 PSI fluctuation. If
pressure is high check for restriction in fuel return system. If pressure is low or fluctuates excessively,
replace return line connector fitting.
STEP 3 CHECKING TRANSFER PRESSURE:
Connect adapter and pressure gage as shown above. At cranking speed, transfer pump pressure should
be 10 PSI m inim um and housing pressure should be at least 2 PSI less than transfer pressure. At idle
speed, transfer pressure should be 30 PSI minimum.
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