1. Drain the fuel tank.
2. Remove the tank gage unit.
3. Thoroughly clean the fuel tank. If the tank is rusted internally, it should be replaced. Clean or replace the fuel pickup filter and check valve assembly.
4. Re-install the fuel tank but leave the lines disconnected at fuel tank area (above the rear axle).
5. Disconnect the main fuel hose at the fuel pump. Using low air pressure, blow out line towards rear of vehicle.
Disconnect the return fuel line at the injection pump, with low air pressure, blow out the line towards the rear of the vehicle.
6. Re-connect the main fuel and return line hoses at the tank. Fill the tank at least 1/4 full with clean diesel fuel.
Re-install fuel tank cap.
7. Remove and discard the fuel filter.
8. Connect the fuel hose to the fuel pump.
9. Re-connect both battery cables.
10. Purge the fuel pump and pump to filter line by cranking the engine until clean fuel is pumped out, catching the fuel in a closed metal container.
11. Install a new fuel filter.
12. Install a hose from the fuel return line (from the injection pump) to a closed metal container with a capacity of at least two gallons.
13. If the engine temperature is above 125 degrees F (52 degrees C), activate the Injection Pump Housing Pressure Cold Advance (H.P.C.A.). This can be done by disconnecting the two lead connectors at the engine temperature switch (located at the rear of the right cylinder head), and bridging the connector with a jumper.
14. Crank the engine until clean fuel appears at the return line. Do not crank the engine for more than 30 seconds at one time. Repeat cranking if necessary with 3 minute intervals between crankings.
15. Remove the jumper from the engine temperature switch connector and reconnect the connector to the switch.
16. Crack open each high pressure line at the nozzles using two wrenches to prevent nozzle damage.
17. Disconnect the lead to the H.P.C.A. solenoid (on the injection pump).
18. Crank the engine until clean fuel appears at each nozzle. Do not crank for more than 30 seconds at one time.
Repeat cranking if necessary, with 3 minute intervals between crankings.
