Fuel Pump: Service and Repair
For operation of the fuel transfer pump primer button, refer to the Air Bleed Procedure.
The fuel transfer pump (fuel lift pump) is located on the left side of the engine and above the starter motor. The mounting bracket/spacer for the fuel heater assembly is located between the engine block and the fuel transfer pump. The fuel heater housing and its bracket assembly must also be removed when removing fuel pump.
REMOVAL
1. Disconnect both negative battery cables at both batteries.
2. Thoroughly clean the area around transfer pump and fuel lines of any contamination.
3. Remove starter motor. Refer to procedure.
4. Place a drain pan below the pump.
5. Remove fuel line fittings at top of both the fuel pump and fuel heater housing. Use back-up wrench to prevent damage to fittings.
6. Remove fuel hose clamps and rubber fuel hose (fuel heater housing-to-fuel pump).
7. The engine camshaft lobe must be at its low point in relation to end of pump piston. Before removing or installing pump, rotate engine until camshaft is at low point. If cam lobe is at high point, removal and installation of pump mounting bolts may be very difficult. Damage to pump may also occur.
NOTE: Locate top dead center (TDC) on cylinder #1.
8. Remove the rubber access plug located in the rear flange of the engine on the exhaust manifold side.
NOTE: Removing the #1 cylinder valve cover and first barring (rotating) the engine clockwise until both intake and exhaust valves are closed will speed up locating engine TDC as described later in Step 10.
9. Insert the barring tool number 7471B through the access hole and into the flywheel housing.
10. While holding tension on the timing pin (toward front of engine), slowly rotate the engine with the barring tool. Hold a slight rearward (pushing) pressure on the barring tool and continue to rotate the tool until the timing pin drops into the machined hole in the back of the camshaft gear. When the pin aligns to the gear, and the intake and exhaust valves are closed at the #1 cylinder, the engine is at the TDC position (compression stroke) at cylinder number 1. After TDC has been established, remove the pin. This will prevent pin damage when barring (rotating) the engine in later steps.
NOTE: The pin is located above the power steering pump, below and to the inside of the fuel injection pump, on the rear of the cam gear housing.
11. After TDC has been established, rotate engine another 180-270 degrees. The camshaft lobe will now be at its lowest point.
12. Remove two pump mounting bolts.
13. Remove the fuel pump and fuel heater assembly from the engine as one unit.
CAUTION: Do not allow pump plunger (piston) to catch on edge of hole in cylinder block during removal. Plunger may slide out and drop into engine.
INSTALLATION
1. While fuel heater is off vehicle, disassemble it and clean pre-filter and screen. Install new seals to fuel heater. Refer to Fuel Heater REMOVAL/INSTALLATION for procedures.
2. Clean the mating surfaces of the fuel heater mounting bracket, the fuel pump and the engine block of any gasket material.
3. Position the new gaskets, the filet heater housing mounting bracket and the fuel pump to the engine.
4. Install the two mounting bolts into the engine. Tighten to 24 N.m (18 ft. lbs.) torque. As these bolts are tightened, the plunger (piston) within the fuel pump is being compressed. Tighten these two bolts alternately to prevent damage to the fuel pump or camshaft.
5. Install fuel line fittings to pump and fuel heater. Tighten to 24 N.m (18 ft. lbs.) torque.
6. Install a new fuel filter. Refer to Fuel Filter/ Water Separator Removal/Installation for procedures.
7. Install starter motor. Refer to procedure.
8. Connect battery cables at both batteries.
9. Bleed air from fuel system. Refer to the Air Bleed Procedure.
10. Start engine and check for leaks.
AIR BLEED PROCEDURE
NOTE: A certain amount of air becomes trapped in the fuel system when fuel system components are serviced or replaced. Bleed the system after fuel system service according to the following procedures.
WARNING: Do not bleed air from the fuel system of a hot engine. Do not allow fuel to spray onto the exhaust manifold when bleeding air from the fuel system.
MANUAL BLEEDING
Some air enters the fuel system when the filters or injection pump supply line are changed. This small amount of air is vented automatically from the injection pump through the fuel drain manifold. This is if the filter was changed according to instructions.
The system may have to be bled manually if:
- The vehicle fuel tank has been allowed to run empty
- The fuel filter is not filled before installation
- The fuel injection pump is replaced
- High-pressure fuel line connections are loosened or lines replaced
- Initial engine start-up or start-up after an extended period of no engine operation.
1. Loosen the low-pressure bleed bolt.
2. Operate the rubber push-button primer on the fuel transfer pump. Do this until the fuel exiting the low-pressure bleed bolt is free of air.
3. Tighten low-pressure bleed screw to 8 N.m (6 ft. lbs.) torque.
FUEL INJECTION PUMP BLEEDING
WARNING: The engine may start when cranking to bleed air from the injection pump place the transmission in neutral or park and set parking brake before engaging the starter motor.
CAUTION: Do not engage the starter motor for more than 30 seconds at a time. Allow two minutes between cranking intervals.
1. Perform the previous procedure: Manual Bleeding.
2. Crank the engine for 30 seconds at a time to allow air trapped in the injection pump to vent out the drain manifold.
- Observe the previous WARNING and CAUTION.
HIGH-PRESSURE FUEL LINE BLEEDING
WARNING: The fuel injection pump supplies high-pressure fuel of as high as 120,000 kPa (17,405 psi) to each individual injector through the high-pressure lines. Fuel under this amount of pressure can penetrate the skin and cause personal injury. Wear safety goggles and adequate protective clothing and avoid contact with fuel spray when bleeding high- pressure fuel lines.
WARNING: Do not bleed air from the fuel system of a hot engine. Do not allow fuel to spray onto the exhaust manifold when bleeding air from the fuel system.
Bleed air from one injector at time.
1. Loosen the high-pressure fuel line fitting at the injector.
2. Crank the engine until all air is bled from the line.
- Do not operate the starter motor for longer than 30 seconds.
- Wait two minutes between cranking intervals.
3. Start the engine and bleed one injector at a time until the engine runs smoothly.
4. Tighten fuel line(s) at injector(s) to 30 N.m (22 ft. lbs.) torque.