When noticeable smoke rises from the exhaust, this problem can be caused by a defective 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.
Fuel System Inspection
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 gallery). (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. Make sure that the vent is not filled with dirt.
- Check the fuel lines for fuel leakage. Make sure that none of the fuel lines have a restriction or a defective bend.
- Clean the screen inside the inlet fitting of the fuel transfer pump.
- Make sure that the pressure regulator (4) is installed correctly, and make sure that the regulator functions properly.
Checking Engine Cylinders Separately
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, "Measurement of Exhaust Temperature" for the procedure for checking the temperatures in the exhaust manifold port.
Start Up Procedure
Note: Refer to Operation and Maintenance Manual, "Engine Starting" in the Operation Section .
Consider the following precautions before starting the engine after work has been done on the fuel system. 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.
Fuel Pressure
| Tools Needed | ||
| Part Number | Part Name | Quantity |
| 1U-5470 | Engine Pressure Group | 1 |
| 3Y-2888 | Connector | 1 |
| 3J-1907 | O-Ring Seal | 1 |
Note: Both the 5P-2720 Probe Adapter Group and the 5P-2718 Pressure Probe can be used with these tools. Use these additional tools to allow the future installation of pressure probes.
The 1U-5470 Engine Pressure Group can be used in order to check the engine's fuel pressures.
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| Illustration 2 | g00284796 |
1U-5470 Engine Pressure Group (1) Pressure indicators. (2) Zero adjustment screw. (3) Pressure indicator. (4) Pressure tap. (5) Pressure indicator. | |
This group has a gauge that is used to register the pressure in the fuel manifolds. Instructions for using this group appear in Special Instruction, SEHS8907.
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| Illustration 3 | g00435719 |
(1) Tube assembly (fuel transfer pump to fuel filter). (2) Tube assembly (fuel filter to fuel gallery). (3) Fitting (fuel return to tank). (4) Regulating orifice and check valve. (5) Cylinder head. (6) Fuel gallery. (7) Fuel outlet port. | |
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| Illustration 4 | g00435720 |
(8) Fuel pressure tap (unfiltered tap). (9) Fuel filter base. (10) Fuel pressure tap (filtered tap). | |
During both normal operating conditions and load conditions, the fuel pressure should register the following range:
- 400 to 525 kPa (58 to 76 psi)
At low idle, the fuel pressure at the fuel filter's inlet should be at the following amount:
- 400 to 435 kPa (58 to 63 psi)
The fuel pressure to fuel gallery (6) should be the same amount, if you subtract the change in pressure (delta P ) across the filter.
With a new filter, the pressure drop across the fuel filter typically registers the following amount:
- 35 kPa (5 psi)
As deposits collect on a fuel filter, the pressure differential will increase. If the fuel pressure in fuel gallery (6) decreases to approximately 69 kPa (10 psi), misfiring may occur.
Fuel pressure regulating orifice (4) is mounted at the fuel return port at the rear of the fuel gallery in the cylinder head. The fuel pressure regulating orifice maintains fuel pressure at low engine rpm. The regulating orifice also contains a spring loaded check valve. The spring loaded check valve prevents the fuel from draining from the fuel gallery back to the fuel tank after engine shutdown.
To check the unfiltered fuel pressure, follow this procedure:
- Remove the plug from fuel pressure tap (8) .
- Install the connector, the seal, and the 1U-5470 Engine Pressure Group to fuel pressure tap (8) .
- Operate the engine.
This will obtain the fuel transfer pump pressure.
To check the fuel pressure in fuel gallery (6) , follow these steps:
- Remove the plug from fuel pressure tap (10) .
- Install the adapter, the seal, and the 1U-5470 Engine Pressure Group to fuel pressure tap (10) .
- Operate the engine.
Note: Make sure that the fuel filter is clean before you check the fuel pressure. A restricted fuel filter causes lower fuel pressure at fuel pressure tap (10) than the fuel pressure at fuel pressure tap (8) .
Hand Fuel Priming Pump (If Equipped)
If the engine's fuel system is run dry, fill the fuel tank. Then prime the fuel system in order to remove any air bubbles from the system.
| NOTICE |
|---|
Do not loosen fuel lines at the fuel manifold. The engine components may be damaged and/or loss of priming pressure may occur when the fuel lines are loosened. |
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| Illustration 5 | g00435721 |
Follow these steps in order to prime the fuel system:
- Locate the red selector lever knob for the fuel priming pump.
- Turn the red selector lever knob away from the fuel filter base by 90 degrees.
This is the PRIME position.
- Operate the priming pump's plunger in order to fill the final fuel filter. Continue until you feel resistance.
Note: You may need to pump the priming pump for 25 times or more in order to fill the fuel filter. Furthermore, you may need up to 75 pump strokes to fill the fuel manifold.
- Push the plunger and tighten the plunger in a clockwise direction. Tighten the plunger by hand.
- Turn the red selector lever knob back to the RUN position.
- After you pressurize the fuel system, promptly crank the engine.
Note: Use the engine starting procedure. Refer to Operation and Maintenance Manual, "Engine Starting" in the Operation Section .
Finding The Top Center Position For No. 1 Piston
| Tools Needed Quantity |
||
| Part Number | Part Name | Quantity |
| 8T-0292 | Bolt | 1 |
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| Illustration 6 | g00435722 |
Top Center Bolt Location (Typical Example) (1) Top center bolt. (2) Timing hole. (3) Flywheel housing. | |
Note: Timing hole (2) can be in one of two positions:
- the left, front face of the flywheel housing
- the right, front face of the flywheel housing
- Remove the plug from timing hole (2) from the front side of the flywheel housing.
Note: Turn the engine with the four large bolts on the front of the crankshaft. Do not use the eight small bolts on the front of the crankshaft pulley.
- Put top center bolt (1) through timing hole (2) in the flywheel housing.
Turn the flywheel in the direction of normal engine rotation. Turn the flywheel until the timing bolt engages with the hole in the flywheel.
Note: If the flywheel is turned beyond the point of engagement, the flywheel must be turned in the direction that is opposite of normal engine rotation. Turn the flywheel by approximately 30 degrees. Then turn the flywheel in the direction of normal engine rotation until the timing bolt engages with the threaded hole. When the No. 1 piston is at the top center position, this procedure will remove the play from the gears.
- Remove the valve cover for the No. 1 cylinder head.
The inlet valves and the exhaust valve for the No. 1 cylinder are fully closed under two conditions:
- No. 1 piston is on the compression stroke.
- The rocker arms can be moved by hand.
If the rocker arms cannot be moved and the valves are slightly open, the No. 1 piston is on the exhaust stroke.
Note: Refer to Testing And Adjusting, "Crankshaft Positions for Valve Lash Setting" .
- No. 1 piston is on the compression stroke.
- After the timing bolt has been installed in the flywheel, complete these procedures, as required:
- Find the cylinders that need to be checked for the stroke position of the crankshaft.
- Find the cylinders that need to be adjusted for the stroke position of the crankshaft.
- When the actual stroke position is identified and the other stroke position is needed, remove the timing bolt from the flywheel.
- Turn the flywheel by 360 degrees in the direction of normal engine rotation.
Note: The timing hole is only used for the following procedures:
- valve lash setting
- electronic timing of the engine
Engine Speed Measurement
| Tools Needed | ||
| Part Number | Part Name | Quantity |
| 1U-6602 | Photo-Tach Group (1) | 1 |
| or | or | |
| 9U-7400 | Multitach | |
| ( 1 ) | This unit is a hand-held service tool. |
Note: The Electronic Service Tools can also be used.
Observation of the electronic service tool display status screen gives the engine rpm.
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| Illustration 7 | g00286276 |
9U-7400 Multitach | |
The 9U-7400 Multitach can measure engine rpm from a magnetic pickup. This magnetic pickup is located in the flywheel housing. The multitach also uses the ability to measure engine rpm from visual engine parts that are rotating.
Note: Refer to Special Instruction, NEHS0605 that is with the 9U-7400 Multitach . This manual gives instructions for the test procedure.
The 1U-6602 Photo-Tach Group is a phototach for general use. This tachometer can only register the basic input frequency on any rotating part that is visible. The basic input frequency is 1 pulse per revolution per piece of reflective tape.
Note: Refer to Special Instruction, SEHS8854 that is with this group. This manual provides instructions for using this tool.
Note: The measurement of engine rpm can be set with the Electronic Service Tool. Refer to Electronic Troubleshooting .