Initial Inspection Of The Fuel System
A problem with the components that send fuel to the engine can cause low fuel pressure. This can decrease engine performance.
Type I Fuel System
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| Illustration 1 | g00713095 |
Type I fuel system (1) Fuel return tube to tank (2) Fuel outlet port to tank (3) Tube assembly from transfer pump to fuel filter (4) Tube assembly from fuel filter to cylinder head (5) Fuel inlet port to fuel transfer pump (6) Screen (7) Fuel filter | |
- Check the fuel level in the fuel tank. Inspect the cap for the fuel tank. Ensure that the vent in the fuel cap is not filled with dirt.
- Check all fuel lines for fuel leakage. The fuel lines must be free from restrictions and faulty bends. Verify that the fuel return line is not collapsed.
- Clean screen (6) inside the inlet fitting of the fuel transfer pump.
- Operate the hand priming pump (if equipped). If excessive resistance is felt, inspect the fuel pressure regulating valve. Make sure that the pressure regulator is installed correctly, and make sure that the pressure regulator functions correctly.
- Install a new fuel filter (7) .
- Cut the used filter open with the 175-7546 Oil Filter Cutter. Inspect the filter for excess contamination. Determine the source of the contamination. Make the necessary repairs.
- Service the primary fuel filter (if equipped).
- Inspect the orifice that is in tube (1). Check the orifice for restrictions that would inhibit proper operation.
- Operate the hand priming pump (if equipped). If uneven resistance is felt, test for air in the fuel. Refer to Testing and Adjusting, "Air in Fuel - Test" for more information.
- Remove any air that may be in the fuel system. Refer to Testing and Adjusting, "Fuel System - Prime".
Type II Fuel System
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| Illustration 2 | g00699649 |
Type II fuel system (1) Fuel outlet port to tank (2) Fuel return tube to tank (3) Tube assembly from transfer pump to fuel filter (4) Tube assembly from fuel filter to cylinder head (5) Fuel inlet port to fuel transfer pump (6) Screen (7) Pressure relief valve (8) Fuel filter | |
- Check the fuel level in the fuel tank. Inspect the cap for the fuel tank. Ensure that the vent in the fuel cap is not filled with dirt.
- Check all fuel lines for fuel leakage. The fuel lines must be free from restrictions and faulty bends. Verify that the fuel return line is not collapsed.
- Clean screen (6) inside the inlet fitting of the fuel transfer pump.
- Operate the hand priming pump (if equipped). If excessive resistance is felt, inspect the fuel pressure regulating valve. Make sure that the pressure regulator is installed correctly, and make sure that the pressure regulator functions correctly.
- Install a new fuel filter (8) .
- Cut the used filter open with the 175-7546 Oil Filter Cutter. Inspect the filter for excess contamination. Determine the source of the contamination. Make the necessary repairs.
- Service the primary fuel filter (if equipped).
- Inspect the orifice that is in tube (2). Check the orifice for restrictions that would inhibit proper operation.
- Operate the hand priming pump (if equipped). If uneven resistance is felt, test for air in the fuel. Refer to Testing and Adjusting, "Air in Fuel - Test" for more information.
- Remove any air that may be in the fuel system. Refer to Testing and Adjusting, "Fuel System - Prime".
Fuel Heater And Water Separator (If Equipped)
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| Illustration 3 | g00839038 |
Fuel heater and water separator (1) Fuel filter (2) Heater (3) Drain valve (water) (4) Temperature sensor | |
Some engines have a fuel heater and a water separator together. The fuel heater is controlled by a thermostat that is located in the base of the unit. The thermostat is preset in order to turn on the heater when the fuel temperature is below 2 °C (36 °F). The fuel heater will turn off when the fuel temperature is 7 °C (45 °F).
In order to check the operation of the heater element, use a continuity light in order to check for current flow through the heater element. Remove the rubber boots from the thermostat and remove the spring spades of the heater element. Use a jumper wire in order to close the temperature sensor.
Remove one wire from the heater element. Check across the two spring spades of the heater element for continuity.
Start Up Procedure
Note: Refer to Operation and Maintenance Manual, "Engine Starting" in the Operation Section.
After work has been done on the fuel system, consider the following precautions before you start the engine. Make sure that you use this starting procedure to start the engine only after the fuel system has been worked on:
- Disconnect the air inlet system from the turbocharger.
- Another person will need to help as a precautionary step. This person should be ready to use the steel plate to cover the turbocharger air inlet if a problem occurs.
Note: Make sure that the steel plate is large enough to cover the entire turbocharger air inlet.
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Be careful when placing the steel plate against the opening on the turbocharger air inlet. To avoid crushed fingers, do not position fingers between the steel plate and the opening on the turbocharger air inlet. Due to excessive suction, the plate can be forcefully pulled against the opening on the turbocharger air inlet. |
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- Start the engine.
Immediately place the steel plate against the opening on the turbocharger air inlet, if the engine operates in one of the following ways:
- The engine runs too fast.
- The engine runs out of control.
Covering the opening will stop the air supply to the engine, so the engine will stop.
- The engine runs too fast.
Road Speed Limiter (If Equipped)
Road speed limiters are supplied by the vehicle manufacturer or at the request of the vehicle manufacturer. Information on operation, maintenance, diagnostics, and parts should be obtained from the vehicle manufacturer.
Inspection With The Engine Running
Either too much fuel for combustion or not enough fuel for combustion can be the cause of a problem in the fuel system. Finding the source of the problem can be difficult, especially when you have smoke that rises from the exhaust. Therefore, work is often done on the fuel system when the problem is really with some other part of the engine.
When noticeable smoke rises from the exhaust, this problem can be caused by a damaged unit injector. This unusual smoke can also be caused by one or more of the reasons that follow:
- Not enough air for good combustion
- An overload at high altitude
- Oil leakage into combustion chamber
- Altitude
- Air inlet and exhaust leaks
- Not enough compression
Note: Refer to Troubleshooting for more information on the fuel system.
Inspection of the Linkage for the Fuel Injection Control
There are two types of linkages for the fuel injection control that are used on these engines.
If you have the current 162-8756 Fuel Injection Control the following steps will not be required.
- Remove the valve cover and the valve cover gasket. Remove the Number 1 rocker arm assembly and the push rods. Refer to the Disassembly and Assembly Service Manual Module for your engine.
Note: Push rods must be reinstalled in the same position. Note the position of the push rods.
Note: Be sure to install the lockwire and the "dealer seal" in order to lock the fuel setting.
- Inspect rivet (1) in order to verify that you do not have the current design 162-8756 Fuel Injection Control .
- Use the following illustrations in order to identify the linkage for the fuel injection control.
- Look at the linkage for the fuel injection control and determine the type of rivet that was used. The current design of the fuel injection control has a washer around the rivet. The direction of the rivet is reversed when the rivet is compared to the former design. The former linkage may need to be modified or the former linkage may need to be replaced. Refer to Special Instruction, REHS0601 if the fuel injection control is the former design.
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| Illustration 4 | g00661677 |
Illustration 4 is of the former 102-7459 Fuel Injection Control. Notice that no washer is on rivet (1). Notice the direction of rivet (1) . | |
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| Illustration 5 | g00661684 |
Illustration 5 is of the current 162-8756 Fuel Injection Control. Notice the washer on rivet (2). Notice the direction of rivet (2) . | |
Checking The Operation Of Individual Cylinders
Low temperature at an exhaust manifold port is an indication of no fuel to the cylinder. This can possibly be an indication of an injector with a defect. An extra high temperature at an exhaust manifold port can be an indication of too much fuel to the cylinder. High temperatures may also be caused by an injector with a defect. The difference between cylinders should be no more than 70 °C (158 °F).
Refer to Testing And Adjusting, "Exhaust Temperature - Test" for the procedure for checking the temperatures in the exhaust manifold port.