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.
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| Illustration 1 | g00435718 |
Fuel System (1) Fuel inlet port (fuel transfer pump) (2) Tube assembly (fuel filter to fuel supply passage) (3) Tube assembly (4) Pressure regulator (5) Tube assembly (fuel transfer pump to fuel filter) (6) Fuel filter (7) Tube assembly | |
- 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 the screen 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 (3). Make sure that the pressure regulator (3) is installed correctly, and make sure that the pressure regulator functions correctly.
- Install a new fuel filter (6) .
- Cut the old filter open with the 175-7546 Oil Filter Cutter Gp. Inspect the filter for excess contamination. Determine the source of the contamination. Make the necessary repairs.
- Service the primary fuel filter (if equipped).
- 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".
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.
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
Note: Refer to Troubleshooting for more information on the fuel system.
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.
Refer to Testing And Adjusting, "Exhaust Temperature - Test" for the procedure for checking the temperatures in the exhaust manifold port.