When noticeable smoke rises from the exhaust, this problem can be caused by a faulty unit injector. This unusual smoke can also be caused by one or more of the reasons that follow:
- Not enough air for good combustion
- Oil leakage into combustion chamber
- Not enough compression
Fuel System Inspection
A problem with the components that send fuel to the engine can cause low fuel pressure. This can decrease engine performance.
- 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 faulty bend.
- Install a new fuel filter. Clean the primary fuel filter.
- Remove any air that may be in the fuel system.
If there is air in the fuel system, use the priming pump to open the drain valve on the fuel injection pump housing. Drain the fuel system until fuel without air flows from the drain line.
Fuel Transfer Pump
When the engine is operating at full load speed, the fuel transfer pump receives fuel from the primary fuel filter. Fuel flows through the ECM and flows through the secondary fuel filters to the fuel injection pump.
Use the following steps to check the fuel transfer pump pressure.
- Disconnect the fuel line from the filter at the fuel injection pump housing inlet.
- Install a tee at the inlet.
- Connect the fuel line to the tee.
- Connect a pressure gauge to the tee.
- Start the engine.
- Fuel is delivered to the fuel pump housing at approximately 414 kPa (60 psi) at full load speed.
If the fuel pressure is not to specifications, stop the engine. Replace the primary fuel filter and replace the secondary fuel filters. Make sure that the fuel lines and the hoses are not plugged or damaged.
Start the engine and check the fuel pressure. If the fuel pressure is not at specifications, repair the fuel transfer pump or replace the fuel transfer pump.
Checking Engine Cylinders Separately
If any of the following conditions occur, check the individual engine cylinders:
- The engine runs rough.
- The engine misfires.
- The exhaust system blows out black smoke.
Use this procedure to check the engine cylinders separately:
- Run the engine at the roughest speed.
- Loosen the fuel line nut at a fuel injection pump. This will stop the flow of fuel to that engine cylinder.
After you shut off an engine cylinder's fuel flow, the engine should run more roughly.
- Tighten the fuel line nut.
- Repeat this maneuver with each engine cylinder in sequence until you discover a loosened fuel line that does NOT affect the engine's performance.
- When you find the engine cylinder that does NOT affect the engine's performance, perform the following operations:
- Test the fuel injection pump.
- Test the fuel injection valve.
When an engine runs at low idle rpm, the temperature of an exhaust manifold can also indicate the condition of a fuel injection valve. A low temperature indicates that no fuel is reaching the cylinder. This can possibly signify that the fuel injection valve has a defect.
When an engine runs at low idle rpm and the temperature of an exhaust manifold is at an extra high temperature, too much fuel is probably flowing into the engine cylinder. This can also signify that the fuel injection valve has a defect.
The most common defects on fuel injection valves include the following defects:
- Any carbon on the tip of a nozzle
- Any carbon in the nozzle orifice
- Orifice wear
- Dirty nozzle screen
Testing Fuel Injection Nozzles
The injectors must be off of the engine before being tested.
Note: Refer to Special Instruction, SEHS7292, "Use Of 5P-4150 Nozzle Assembly" for more information.
Fuel Injection Lines
Fuel from the fuel injection pumps is sent through the fuel injection lines to the fuel injection valves.
Each fuel injection line of an engine has a special design. Each fuel injection line must be installed in a certain location. When fuel injection lines are removed from an engine, put identification marks or put tags on the fuel lines as the lines are removed. This will allow the lines to be installed in the correct location.
The nuts that hold a fuel injection line to an injection valve and to an injection pump must be kept tight. Tighten the fuel line nuts to 40 ± 7 N·m (30 ± 5 lb ft).
Fuel Bypass Valve
The fuel bypass valve controls fuel pressure to the fuel injection pump. At full speed, the pressure is limited to 230 ± 35 kPa (33 ± 5 psi).
Finding the Top Center Position for No. 1 Piston
| Tools Needed | ||
| 9S-9082 | Engine Turning Tool | 1 |
Note: The starting position for all timing procedures is with the No. 1 piston at the top center position on the compression stroke.
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| Illustration 1 | g00361852 |
Locating the top center position (typical example) (1) The storage location for the timing bolt. (2) Plug. (3) Bolt. (4) Cover. | |
- Remove the timing bolt (1), the bolt (3), and the cover (4) .
- Remove the plug (2) .
- Install 9S-9082 Engine Turning Tool (5) in the housing.
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| Illustration 2 | g00361853 |
9S-9082 Engine Turning Tool is installed. (1) The installed timing bolt. (5) 9S-9082 Engine Turning Tool . | |
- Once plug (2) has been removed, insert the timing bolt (1) through the hole. Hold the timing bolt (1) against the flywheel.
- Turn the flywheel in the direction of normal engine rotation until the timing bolt engages with the threaded hole. The No. 1 piston is at the top center position on the engine.
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 left front valve cover. Look at the valves of No. 1 cylinder. The valves will be closed if the No. 1 piston is on the compression stroke. You can move rocker arms up and down with your hand. If the No. 1 piston is not on the compression stroke, perform the following steps.
 | |
| Illustration 3 | g01246025 |
Cylinder and valve location (A) Inlet. (B) Exhaust. (C) Fuel injection pumps. | |
- Remove the timing bolt from the flywheel.
- Rotate the crankshaft counterclockwise by 360 degrees. Install the timing bolt.
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.
Checking Engine Timing with 8T-5300 Engine Timing Indicator Group and 8T-5301 Diesel Engine Timing Adapter Group
| Tools Needed | ||
| 8T-5300 | Engine Timing Indicator Group | 1 |
| 8T-5301 | Diesel Engine Timing Adapter Group | 1 |
 | |
| Illustration 4 | g00339402 |
8T-5300 Engine Timing Indicator Group (1) 8T-5250 Engine Timing Indicator. (2) 5P-7366 Power Cable. (3) 6V-2197 Magnetic Transducer. (4) 5P-7362 Cable. (5) 6V-2199 Transducer Adapter and 6v-3093 Transducer Adapter. (6) 8D-4644 Corner . | |
The 8T-5300 Timing Indicator Group must be used with the 8T-5301 Diesel Engine Timing Adapter Group.
 | |
| Illustration 5 | g00339406 |
8T-5301 Diesel Engine Timing Adapter Group (7) 5P-7437 Adapter. (8) 6V-2198 Cable. (9) 5P-7436 Adapter. (10) 6V-7910 Transducer. (11) 5P-7435 Adapter. (12) 6V-3016 Washer . | |
When you check for the dynamic timing on an engine without a mechanical advance, Caterpillar Inc. recommends the recording of the calculations for the dynamic timing onto paper. Then, the service person can create a graph of the dynamic advance.
Note: Worksheets are available in pads of fifty. Order one Special Instruction, SEHS8140. See Special Instruction, SEHS8580 for information on calculating the timing curve.
After the timing values are calculated and the timing values are plotted, the dynamic timing should be checked with the 8T-5300 Engine Timing Indicator Group .
- Operate the engine from 1000 rpm (base rpm) to high idle.
- Continue running the engine now from high idle to 1000 rpm (base rpm).
Unstable readings often appear below 1000 rpm.
- Record the dynamic timing at each 100 rpm and at the specified speeds during acceleration and during deceleration.
- Finally, plot the results onto the worksheet. Review the plotted values.
Use Special Instruction, SEHS8580 to see the correct specifications for calculating the timing curve.
You can find these specifications in three places:
- The Operating Instructions inside the lid of the 8T-5300 Engine Timing Indicator Group
- The Special Instruction, SEHS8580
- The Engine Information Plate for the performance specification number
The performance specification number can be used to refer to the TMI. Here, you will find the correct timing specifications to use.
- The engine must be stopped before installing the timing indicator.
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Personal injury or death can result from not following the proper procedures. To avoid the possibility of injury or death, follow the established procedure. |
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| Illustration 6 | g00339033 |
Transducer in position (10) 6V-7910 Transducer. (13) Fuel injection line for No. 1 cylinder. | |
- A high pressure fuel line must be disconnected and a probe must be installed into the flywheel housing.
- Disconnect the fuel injection line (13) for the No. 1 cylinder. Slide the nut upward. Slide the nut out of the way. Attach the 5P-7436 Adapter (9). Tighten 5P-7436 Adapter (9) onto the pump bonnet. Turn adapter (9) onto the pump bonnet. Continue until the top of the bonnet's threads line up with the bottom of the opening in adapter (9) .
- Attach 5P-7435 Adapter (11) onto injection transducer (10). Then, connect 5P-7435 Adapter (11) in the opening of 5P-7436 Adapter (9) .
- Place fuel injection line (13) on top of 5P-7435 Adapter (11). Install 5P-7437 Adapter (7). Tighten the adapter to a torque of no more than 40 N·m (30 lb ft).
- Remove the plug (14) from the flywheel housing. Install transducer adapter (5) into the hole that is remaining from the plug's removal. Tighten transducer adapter (5) only by a small amount.
 | |
| Illustration 7 | g00361933 |
Timing hole location (starting motor is not mounted) (14) Plug. | |
- Push magnetic transducer (3) into transducer adapter (5) until this adapter contacts the flywheel. Pull the magnetic transducer (3) out of the transducer adapter by 1.5 mm (0.06 inch). Then, lightly tighten the knurled locknut.
- Connect the cables from the magnetic transducer (3) to 8T-5250 Engine timing indicator (1). Calibrate the indicator, and make any necessary adjustments.
Note: See Special Instruction, SEHS8580 for more information on the calibration procedure.
 | |
| Illustration 8 | g00361934 |
Transducer in position (starter not mounted) (3) 6V-2197 Magnetic Transducer . | |
- Start the engine, and allow the engine to reach operating temperature. Then, run the engine at approximately one half throttle for eight to ten minutes. After this amount of time, measure the engine's timing.
- Run the engine at increments of 100 rpm between 1000 rpm (base rpm) and high idle. Record the readings for engine timing, and then plot these readings onto a graph.
Note: Use smaller increments to pinpoint the times when the timing advance starts. You can also use smaller increments to pinpoint the times when the timing advance stops.
- If the automatic timing advance is not correct, repair the automatic timing advance unit, or replace the automatic timing advance unit. There is no adjustment to the unit.
Fuel System Adjustments (On Engine)
Camshaft Timing for Fuel Injection Pump
| Tools Needed | ||
| 6V-4186 | Fuel Pump Timing Pin | 1 |
- Position the No. 1 piston at the top center position on the compression stroke. Refer to "Finding The Top Center Position For No. 1 Piston".
Note: A 1P-3566 Hex Bit 9/16 inch cut to a length of 25.4 mm (1.00 inch) can be used to remove the plug from the front end of the injection pump housing.
- Remove the plug at the front end of the fuel injection pump housing.
 | |
| Illustration 9 | g00361935 |
Remove the timing pin plug (typical example) (1) Timing pin plug. | |
- Install 6V-4186 Fuel Pump Timing Pin (end with taper) through the hole in the injection pump housing.
- If the timing is correct, the timing pin will go into the notch in the camshaft and the timing bolt will turn into the threaded hole in the flywheel. If the timing is NOT correct, the timing must be changed.
Note: If the timing is correct, BE SURE TO REMOVE THE TIMING PIN AND BE SURE TO REMOVE THE TIMING BOLT.
If the timing was NOT correct, remove the timing pin. Use the procedure that follows to change the timing.
- Remove cover (2) that covers the four bolts of the automatic timing advance unit.
Show/hide table
Illustration 10 g00361936
Access cover to automatic timing advance unit (typical example)
(2) Cover.
- MAKE SURE that the timing pin is removed before the bolts are loosened. Loosen the four bolts (3) that hold the automatic timing advance unit (4) onto the fuel pump camshaft.
Show/hide table
Illustration 11 g00361938
Automatic timing advance unit (typical example)
(3) Bolts. (4) Automatic timing advance unit.
- Tighten the bolts (3) with fingers until there is a small amount of friction (slight drag) between the retainer and the automatic timing advance unit (4). This friction will hold the unit against the timing gears. This prevents play (backlash) when gears are turned to the correct position.
- Remove the timing bolt. Turn the flywheel until the timing pin will go into the groove in the camshaft of the fuel injection pump.
- With the timing pin installed, turn the flywheel clockwise a minimum of 30 degrees. This is the opposite direction of the engine rotation. When the No. 1 piston is at the top center position, this procedure will remove the play from the gears.
- Then, turn the flywheel in the direction of normal engine rotation until the timing bolt engages with the threaded hole.
- Tighten the bolts (3) to 25 N·m (20 lb ft). Then, remove the timing pin from the injection pump housing.
- Tighten the bolts (3) to 230 ± 15 N·m (170 ± 11 lb ft). Then, remove the timing bolt from the flywheel.
- Rotate the crankshaft counterclockwise for two revolutions. Check the timing again. If the timing bolt can be installed in the flywheel and the timing pin can be installed in the camshaft, the timing is correct.
- If the timing is not correct, refer to 4.b through 4.h.
Note: If timing is correct, BE SURE TO REMOVE THE TIMING PIN AND BE SURE TO REMOVE THE TIMING BOLT.
Rack Position Sensor Calibration
Refer to 3412C Generator Set Engine Electronic Troubleshooting Guide, "5.0 Electronic Subsystem Functional Test, Rack Control Test, P-531: Rack Position Sensor/Calibration".
Engine Speed Sensor Adjustment
Refer to 3412C Generator Set Engine Electronic Troubleshooting Guide, "5.0 Electronic Subsystem Functional Test, Engine Circuit Test, P-522: Main Engine Speed Sensor/Adjustment".