Two electric pumps are used on fuel injected models; a low pressure boost pump mounted in the fuel tank and a high pressure pump mounted on the vehicle frame.
The low pressure pump is used to provide pressurized fuel to the inlet of the high pressure pump and helps prevent noise and heating problems. The externally mounted high pressure pump is capable of supplying 15.9 gallons of fuel an hour. System pressure is controlled by a pressure regulator mounted on the engine.
See Figure 1
These trucks employ a single, high pressure pump which is part of the modular, In-Tank Reservoir (ITR) assembly. Besides the pump, the ITR consists of a venturi jet pump, a supply check valve and a shuttle selector valve. All this is mounted on the fuel gauge sender flange. The sending unit is separate from the ITR module.
REMOVAL & INSTALLATIONOn internally mounted pumps, tank removal is required. Frame mounted models can be accessed from under the vehicle. Prior to servicing, release the fuel system pressure. Refer to the applicable Fuel Injection System procedures listed in this section for details. Disconnect the negative battery cable prior to pump removal.
In-Tank PumpSee Figures 2 and 3
- Release the fuel system pressure. Disconnect the negative battery cable.
- Remove the fuel tank as described below.
- On steel tanks:
- Disconnect the wiring at the connector.
- Remove all dirt from the area of the sender.
- Disconnect the fuel lines.
- Turn the locking ring counterclockwise to remove it. There is a wrench designed for this purpose. If the wrench is not available, you can loosen the locking ring by placing a WOOD dowel against on the the tabs on the locking ring and hammering it loose. NEVER USE A METAL DRIFT!
- Lift out the fuel pump and sending unit. Discard the gasket.
- On plastic tanks:
- Disconnect the wiring at the connector.
- Remove all dirt from the area of the sender.
- Disconnect the fuel lines.
- Turn the locking ring counterclockwise to remove it. A band-type oil filter wrench is ideal for this purpose. Lift out the fuel pump and sending unit. Discard the gasket.
- Place a new gasket in position in the groove in the tank.
- Place the sending unit/fuel pump assembly in the tank, indexing the tabs with the slots in the tank. Make sure the gasket stays in place.
- Hold the assembly in place and position the locking ring.On steel tanks, turn the locking ring clockwise until the stop is against the retainer ring tab.On plastic tanks, turn the retaining ring clockwise until hand-tight. There is a special too available to set the tightening torque for the locking ring. If you have this tool, torque the ring to 40-55 ft. lbs. (54-75 Nm). If you don't have the tool, just tighten the ring securely with the oil filter wrench.
- Make sure the gasket is still in place.
- Connect the fuel lines and wiring.
- Install the tank.
See Figures 4 and 5
- Disconnect the negative battery cable.
- Depressurize the fuel system.
- Raise and support the rear of the vehicle on jackstands.
- Disconnect the inlet and outlet fuel lines.
- Remove the pump from the mounting bracket.
- Install in reverse order, make sure the pump is indexed correctly in the mounting bracket insulator.
- Operate the engine at the specified idle rpm.
- Open the hose restrictor and catch the fuel in the container while observing the time it takes to pump 1 pint. 1 pint should be pumped in 20 seconds. If the pump does not pump to specifications, check for proper fuel tank venting or a restriction in the fuel line leading from the fuel tank to the carburetor before replacing the fuel pump.
Fuel Injectors
REMOVAL & INSTALLATION
See Figures 1, 2, 3, 4, 5, 6 and 7
- Relieve the fuel system pressure.
- For all except 7.5L engines, remove the upper intake manifold assembly.
- Remove the fuel rail.
- Disconnect the wiring at each injector.
- Pull upward on the injector body while gently rocking it from side-to-side.
- Inspect the O-rings on the injector for any sign of leakage or damage. Replace any suspected O-rings.
- Inspect the plastic cap at the top of each injector and replace it if any sign of deterioration is noticed.
- Lubricate the O-rings with clean engine oil ONLY!
- Install the injectors by pushing them in with a gentle rocking motion.
- Connect the electrical wiring.
- Install the fuel rail.
- If applicable, install the upper intake manifold.
Fuel Injector Pressure Test
- Connect pressure gauge T80L-9974-A, or equivalent, to the fuel pressure test fitting. Disconnect the coil connector from the coil. Disconnect the electrical lead from one injector and pressurize the fuel system. Disable the fuel pump by disconnecting the inertia switch or the fuel pump relay and observe the pressure gauge reading.
- Crank the engine for 2 seconds. Turn the ignition OFF and wait 5 seconds, then observe the pressure drop. If the pressure drop is 2-16 psi (14-110 kPa), the injector is operating properly. Reconnect the injector, activate the fuel pump, then repeat the procedure for other injector.
- If the pressure drop is less than 2 psi (14 kPa) or more than 16 psi (110 kPa), switch the electrical connectors on injectors and repeat the test. If the pressure drop is still incorrect, replace the disconnected injector with one of the same color code, then reconnect both injectors properly and repeat the test.
- Disconnect and plug the vacuum hose at EGR valve. It may be necessary to disconnect the idle air control valve and use the throttle body stop screw to set the engine speed. Start and run the engine at 1,800 rpm (2,000 rpm on 1984 and later models). Disconnect the left injector electrical connector. Note the rpm after the engine stabilizes (around 1,200 rpm). Reconnect the injector and allow the engine to return to high idle.
- Perform the same procedure for the right injector. Note the difference between the rpm readings of the left and right injectors. If the difference is 100 rpm or less, check the oxygen sensor. If the difference is more than 100 rpm, replace both injectors.
Fuel Pressure Regulator
REMOVAL & INSTALLATION
Except Lightning Engine
See Figures 1, 2, 3, 4 and 5
- Relieve the fuel system pressure.
- Disconnect the vacuum line at the regulator.
- Remove the 3 Allen screws from the regulator housing.
In some cases the factory bent the fuel line over one of the 3 Allen screws making it difficult to remove with an Allen wrench. A pair of pliers may have to be used to break the screw loose so it can be unthreaded by hand.
- Remove the regulator.
- Inspect the regulator O-ring for signs of deterioration or damage. Discard the gasket.
- Lubricate the O-ring with clean engine oil ONLY!
- Make sure that the mounting surfaces are clean.
- Using a new gasket, install the regulator. Tighten the retaining screws to 40 inch lbs. (4.5 Nm).
- Connect the vacuum line.
- Relieve the fuel system pressure.
- Remove the fuel supply manifold.
- Remove the 3 Allen screws from the regulator housing.
- Remove the regulator.
- Inspect the regulator O-ring for signs of deterioration or damage. Discard the gasket.
- Lubricate the O-ring with clean engine oil ONLY!
- Make sure that the mounting surfaces are clean.
- Using a new gasket, install the regulator. Tighten the retaining screws to 40 inch lbs. (4.5 Nm).
- Install the fuel supply manifold.
Tank Assembly
REMOVAL & INSTALLATION
Except Bronco
See Figures 1 through 10
STEEL MID-SHIP TANK(S)
- On vehicles with a single fuel tank, disconnect the battery ground cable, then, drain the fuel from the tank into a suitable container by either removing the drain plug, if so equipped, or siphoning through the filler cap opening.
- On vehicles with dual tanks, drain the fuel tanks by disconnecting the connector hoses, then disconnect the battery ground cable.
- Disconnect the fuel gauge sending unit wire and fuel outlet line.
- Disconnect the air relief tube from the filler neck and fuel tank.
- Loosen the filler neck hose clamp at the fuel tank and pull the filler neck away from the tank.
- Remove the retaining strap mounting nuts and/or bolts and lower the tank(s) to the floor.
- If a new tank is being installed, change over the fuel gauge sending unit to the new tank.
- Install the fuel tank(s) in the reverse order of removal. Torque the strap nuts to 30 ft. lbs. (41 Nm).
- Drain the fuel from the tank into a suitable container by either removing the drain plug, if so equipped, or siphoning through the filler cap opening.
- Disconnect the battery ground cable(s).
- Remove the skid plate and heat shields.
- Disconnect the fuel gauge sending unit wire at the tank.
- Loosen the filler neck hose clamp at the fuel tank and pull the filler neck away from the tank.
- Disconnect the fuel line push-connect fittings at the fuel gauge sending unit.
- Support the tank. Remove the retaining strap mounting bolts and lower the tank to the floor.
- If a new tank is being installed, change over the fuel gauge sending unit to the new tank.
- Install the fuel tank(s) in the reverse order of removal. Torque the strap bolts to 12-18 ft. lbs. (16-24 Nm).
- Raise the rear of the truck.
- Disconnect the negative battery cable.
- On trucks with a single tank, disconnect the fuel gauge sending unit wire at the fuel tank. Remove the fuel drain plug or siphon the fuel from the tank into a suitable container.
- On vehicles with dual tanks, drain the fuel tanks by disconnecting the connector hoses.
- Disconnect the fuel line push-connect fittings at the fuel gauge sending unit.
- Loosen the clamps on the fuel filler pipe and vent hose as necessary and disconnect the filler pipe hose and vent hose from the tank.
- If the tank is the metal type, support the tank and remove the bolts attaching the tank support or skid plate to the frame. Carefully lower the tank or tank/skid plate assembly and disconnect the vent tube from the vapor emission control valve in the top of the tank. Finish removing the filler pipe and filler pipe vent hose if not possible previously. Remove the tank from under the vehicle.
- If the tank is the plastic type, support the tank and remove the bolts attaching the combination skid plate and tank support to the frame. Carefully lower the tank and disconnect the vent tube from the vapor emission control valve in the top of the tank. Finish removing the filler pipe and filler pipe vent hose if it was not possible previously. Remove the skid plate and tank from under the vehicle. Remove the skid plate from the tank.
- If the sending unit is to be removed, turn the unit retaining ring counterclockwise and remove the sending unit, retaining ring and gasket. Discard the gasket.
- Install the tank in the reverse order of removal. With metal tanks, use thread adhesive such as Loctite® on the bolt threads, and torque these bolts to 27-37 ft. lbs. (37-50 Nm). With plastic tanks, DO NOT use thread adhesive. Torque the bolts to 25-35 ft. lbs. (34-47 Nm).
See Figures 9 and 10
- Raise and support the rear end on jackstands.
- Disconnect the negative battery cable.
- Disconnect fuel gauge sending unit wire at fuel tank.
- Remove the fuel drain plug or siphon the fuel from the tank into a suitable container.
- Loosen the fuel line hose clamps, slide them forward and disconnect fuel line at the fuel gauge sending unit.
- Loosen the clamps on the fuel filler pipe and vent hose as necessary and disconnect the filler pipe hose and vent hose from the tank.
- Support the tank and remove the lower attaching bolts or skid plate bolts supporting the tank to the frame. Carefully lower the tank or tank/skid plate assembly and disconnect the vent tube from the vapor emission control valve in the top of the tank. Finish removing the filler pipe and filler pipe vent hose if not possible previously. Remove the tank from under the vehicle.
- If the sending unit is being removed, turn the unit's retaining ring counterclockwise and remove the sending unit, retaining ring and gasket. Discard the gasket.
- Install the tank in the reverse order of removal. Use threadlocking compound on the bolt threads and torque the bolts to 27-37 ft. lbs. (37-50 Nm).
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