Diesel MFI Pump: Testing and Inspection
Fig. 41 Roosa-Master pump pressure tap plug location:
Fig. 42 CAV pump torque screw location:
1982-83
1. Remove air crossover and install screen covers J-29657 or other suitable covers.
2. On Roosa-Master pumps, remove pressure tap plug. On CAV pumps, remove torque screw, Figs. 41 and 42. If equipped with torque screw, to avoid disturbing adjustment add a second nut to lock nut, then back out screw with nuts attached.
3. Attach low pressure gage to adapters.
4. Connect magnetic pick-up tachometer.
5. With gear shift lever in park position and parking brake on, check pressure with engine running at 1000 RPM. Pressure should be between 8-12 psi with no more than 2 psi fluctuation.
6. If pressure is at 0, check operation of housing pressure cold advance as follows:
a. Remove electrical connector from housing pressure cold advance terminal, Figs. 43 and 44. If pressure remains at 0, remove injection pump cover and check operation of advance solenoid. If it is binding, repair or replace parts as necessary.
b. If pressure is as specified with housing cold pressure advance electrical connector disconnected, check operation of temperature switch located in cylinder head bolt.
7. If pressure is not within specifications, replace fuel return line connector assembly or check for restricted HPAA, if equipped.
8. Remove tachometer, pressure gauge and adapter.
9. Install a new pressure tap plug seal on pressure tap plug and install plug into pump housing.
10. Remove screened covers and install air crossover.
Fig. 45 Injection pump housing fuel pressure specifications. 1984 models:
1984
1. Ensure that temperature switch is functioning properly.
2. Remove air cleaner and install protective cover J-26996-1 or equivalent.
3. Disconnect fuel return line from return line connector.
4. Remove return line connector from injection pump cover.
5. Push Housing Pressure Cold Advance (HPCA) solenoid plunger into solenoid.
6. Disconnect electrical connector at HPCA terminal and, using suitable jumper wire, apply 12 volts to HPCA solenoid.
7. If HPCA solenoid plunger does not extend fully, remove pump cover and repair or replace HPCA terminal.
8. Install suitable adapter in pump cover, connect return line to adapter, and attach low pressure gauge and suitable tachometer to adapter.
9. Apply parking brake, block drive wheels, place selector lever in ``PARK'' and check pressure at 1000 RPM. Pressure should be as shown, Fig. 45.
10. If pressure is too low, replace fuel return line connector assembly.
11. If pressure is too high, remove return line at adapter pump and install a fitting with short piece of hose to allow return flow to empty into suitable container.
12. If pressure drops, clear restriction in fuel line.
13. If pressure does not drop in step 13, replace fuel return line connector assembly, then check timing, adjusting as necessary.
14. If pressure is still too high, repair or replace injection pump as necessary.
15. Remove tachometer, pressure gauge and adapter.
16. Using new O-ring, install fuel return line connector into pump cover.
17. Connect fuel return line to return line connector.
18. Start engine and check for leaks.
19. Remove protective cover and install air crossover.
Procedure ``A''
1. Block drive wheels, apply parking brake and shift transaxle to Park.
2. Start engine and run until normal operating temperature is reached, then stop engine.
3. Remove air cleaner cover.
4. Remove Manifold Absolute Pressure (MAP) sensor retainer and position MAP sensor aside, leaving wiring and vacuum hose attached.
5. Remove air cleaner assembly, then the air crossover pipe.
6. On models equipped with external Exhaust Gas Recirculation (EGR), disconnect vacuum hose from EGR valve.
7. On all models, remove Metering Valve Sensor (MVS) adjustment hole plug.
8. Install washers onto tool No. J-28526, then attach a suitable pressure gauge to tool.
9. Disconnect electrical connectors from Housing Pressure Cold Advance (HPCA) solenoid.
10. Disconnect Housing Pressure Altitude Advance (HPAA) electrical connector from engine wiring harness.
11. Attach suitable tachometer to engine, then start engine.
12. Inspect for fuel leaks and correct as necessary.
13. Increase engine idle speed to 1000 RPM and note pressure reading.
Procedure ``B''
1. Stop engine, then remove line fitting from pressure regulator.
2. Insert a 1/8 inch Allen wrench into pressure regulator and rotate adjustment screw as necessary to obtain 10 psi pressure. Rotate the adjustment screw counterclockwise to decrease pressure or clockwise to increase pressure. One complete turn of the screw will alter pressure by approximately 3.2 psi.
3. Check injection pump timing and adjust as necessary as described under ``Injection Pump Timing.''
Procedure ``C''
If housing pressure is very low, or cannot be brought to 9---11 psi by adjusting the regulator, the Housing Pressure Cold Advance (HPCA) pressure regulator or solenoid is defective.
1. Remove pressure regulator from pump.
2. Apply a maximum of 30 psi air pressure through regulator at both ends (first from pump side, then from outlet side). The check ball should seat when applying air from outlet side.
3. Replace pressure regulator if operation is not satisfactory. If regulator is contaminated with foreign matter, remove injection pump cover to determine source of contamination.
4. Check HPCA solenoid as follows:
a. Connect electrical connectors to HPCA solenoid.
b. Turn ignition switch to Run position and ensure HPCA solenoid plunger is extended upward, then turn ignition switch to Off or Lock position.
c. When ignition switch is turned Off, solenoid plunger should retract automatically or be able to be pushed back with light pressure applied. If not, remove injection pump cover and repair or replace HPCA solenoid as necessary.
Procedure ``D''
1. Disconnect fuel return line from Housing Pressure Altitude Advance (HPAA) inlet.
2. Attach a suitable hose to pipe outlet and position opposite end of hose into a drain pan.
3. Start engine and observe pressure reading.
4. If housing pressure is now 9-11 psi, there is a restriction in HPAA solenoid assembly, hoses, tank unit, or other fuel return lines.
Procedure ``E''
1. Reconnect injection pump fuel return line to Housing Pressure Altitude Advance (HPAA) solenoid inlet.
2. Disconnect fuel return line from HPAA solenoid outlet.
3. Attach a suitable hose to HPAA outlet and position opposite end of hose into a drain pan.
4. Start engine.
Procedure ``F''
1. Remove Housing Pressure Altitude Advance (HPAA) solenoid assembly from engine.
2. Apply a maximum of 30 psi air pressure through both sides of solenoid (first from pump side, then from outlet side). If air does not flow freely in both directions, replace solenoid.
3. Remove pressure regulator from solenoid and check solenoid plunger. If plunger does not move freely, replace solenoid.
4. Install HPAA solenoid assembly, then disconnect electrical connector from Manifold Absolute Pressure (MAP) sensor.
5. Start engine and observe housing pressure, which should be 3---5 psi.
6. If housing pressure is not within specifications, adjust pressure regulator as follows:
a. Remove HPAA assembly from engine.
b. Remove line fitting from pressure regulator.
c. Insert a 1/8 inch Allen wrench into pressure regulator and rotate adjustment screw as necessary to obtain 3---5 psi pressure. Rotate the adjustment screw counterclockwise to decrease pressure or clockwise to increase pressure. One complete turn of the screw will alter pressure by approximately 3.2 psi.