Fuel System Identification
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| Illustration 1 | g01247195 |
Fuel injection pump and governor drive group (typical example) | |
- The part number is stamped in this location.
| 3412C Fuel System With Caterpillar Dashpot Governors | ||
| Engine Arrangement | In. Pump & Governor Group or Drive | Injection Pump |
| 148-3590 | 4W-8296 | 4N-1101 |
| 148-3592 | ||
| 148-3594 | ||
| 166-8581 | ||
| 166-8583 | ||
| 166-8585 | ||
| 148-3598 | 7W-7131 | |
| 148-3600 | ||
| 166-8589 | ||
| 166-8591 | ||
| 186-4817 | ||
| 149-7505 | 131-3239 | |
| 186-4816 | 108-3698 | |
| 186-4819 | 108-3697 | |
| 148-3591 | 4W-6074 | 4W-6073 |
| 148-3593 | ||
| 148-3595 | ||
| 148-3599 | ||
| 148-3601 | ||
| 166-8582 | ||
| 166-8584 | ||
| 166-8586 | ||
| 166-8590 | ||
| 166-8592 | ||
| 171-5336 | ||
| 187-0557 | ||
| 189-8854 | ||
| 149-7506 | 131-3240 | 131-3281 |
Fuel System
Either too much fuel for combustion or not enough fuel for combustion can be the cause of a problem in the fuel system. It is difficult to evaluate the source of the problem, especially when smoke 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 worn 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.
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 Injector 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 2 | 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 3 | g00361853 |
The 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.
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| Illustration 4 | 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 |
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| Illustration 5 | 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) 5P-7362 Cable, 6V-2199 Transducer Adapter and 6V-3093 Transducer Adapter (6) 8D-4644 Corner | |
The 8T-5300 Timing Indicator Group must be used with 8T-5301 Diesel Engine Timing Adapter Group.
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| Illustration 6 | 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 engine timing indicator group.
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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 7 | 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.
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| Illustration 8 | 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.
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| Illustration 9 | g00361934 |
Transducer in position (starting motor is 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 the 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.
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| Illustration 10 | 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 11 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 12 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 fuel injection pump camshaft.
- 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.
Governor Adjustments
| Tools Needed | ||
| Part Number | Part Name | Quantity |
| 9U-7400 | Multitach | 1 |
| NOTICE |
|---|
A service technician with training in governor adjustments is the only one to make the adjustment to the set point rpm. |
Check engine rpm with an accurate tachometer. Refer to "Measuring Engine Speed" for more information about checking engine rpm.
High and Low Idle Adjustment
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| Illustration 13 | g00342573 |
Adjustment screw cover (1) Cover | |
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Personal injury can result from rotating and moving parts. Moving fan blades and moving parts will throw or cut any object or tool that falls or is pushed into them. Ensure that no one is working on, underneath or close to the machine before starting the engine. Ensure the area is free of personnel. |
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Start the engine and check the low idle rpm. Check the high idle rpm. Refer to Fuel Setting Information for the correct low idle and the correct high idle rpm.
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| Illustration 14 | g00342632 |
Idle adjustment (2) High idle screw (3) Low idle screw | |
If an adjustment is necessary, remove cover (1) and use the following procedure.
- To adjust the low idle rpm, move the governor linkage to the LOW IDLE position. Turn screw (3). Increase the engine speed and then return the linkage back to LOW IDLE position. Recheck the setting.
- Move the governor linkage to HIGH IDLEposition. Turn screw (2) in order to adjust the HIGH IDLE rpm. When the specific rpm setting is made, move the governor control to reduce engine speed, then move the linkage to HIGH IDLE. Recheck the setting. Repeat this procedure until the rpm setting is correct.
- When the governor adjustment is correct, install the cover on top of the governor.
When the cover is installed on the governor, the idle adjustment screws fit into holes in the cover. The shape of the holes will not allow the idle adjustment screw to turn after the idle adjustment is completed and the cover is installed.
- Install a new wire and install a new seal to the cover bolt.
Dashpot Adjustment
The dashpot governor does not work properly when one of the following items occur:
- No stability of rpm
- Slow changes of rpm when the engine load changes.
- Variable performance
Adjust the governor if one of the problems occur.
- With the engine in operation, loosen adjustment screw (2) on the top of the governor. Loosen the screw (2) two to three turns. The oil flow will clean the orifice in the oil passage. Next, tighten screw (2) only 1/16 of one turn to 1/4 turn of one turn. This will allow the correct amount of oil flow to the dashpot reservoir.
Note: The adjustment controls oil flow into the top reservoir. Too much oil flow will fill the governor with oil. This will decrease performance. Too little oil flow will allow the reservoir to become empty. This will allow air in the dashpot chamber. This will allow the governor to hunt. A hunting condition is when the engine speed constantly increases or decreases.
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| Illustration 15 | g00342634 |
Side view of governor (1) Adjustment screw for dashpot (2) Adjustment screw for supply oil to reservoir | |
- An adjustment screw (1) is located on the right side of the governor. Loosen adjustment screw (1) two to three turns. The oil flow into and out of the dashpot chamber will clean the orifice in the oil passage. Next, tighten adjustment screw (1) until it stops. Then, loosen adjustment screw (1) 1/4 of one turn to one full turn. This will make the correct restriction for the dashpot operation. The exact point of adjustment is the point the governor provides the best performance.
Note: This adjustment controls the amount of restriction of the oil flow into and out of the dashpot chamber. Too much oil flow will cause the governor to hunt. Too little flow will cause a slow action of the governor.
Measuring Engine Speed
| Required Tools | ||
| Part Number | Part Name | Quantity |
| 9U-7400 | Multitach | 1 |
| 6V-4950 | Speed Pickup | 1 |
 | |
| Illustration 16 | g00300249 |
9U-7400 Multitach | |
The 9U-7400 Multitach can measure engine speed from a tachometer drive on the engine. The multitach also has the ability to measure engine speed from visual engine parts in rotation.
Refer to Special Instruction, SEHS7807 for instructions about the test procedure.
The 6V-4950 Speed Pickup is another diagnostic tool accessory that can be used with the 9U-7400 Multitach. The speed pickup can be used on all Caterpillar Diesel Engines that are equipped with 6 mm (0.25 inch) single wall fuel injection lines. Engine speed can be measured quickly and automatically with this pickup group. The accuracy is ± 1 rpm.
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| Illustration 17 | g01247197 |
6V-4950 Speed Pickup (1) 6V-6113 Pickup Amplifier (2) 6V-6114 Pickup | |
Refer to Special Instruction, SEHS8029 for instructions on using the 6V-4950 Speed Pickup .
Check Set Point (Balance Point)
An engine relies on set point for the correct operation of the engine. The set point check of the engine is a method that will diagnosis engine performance.
There is a new, more accurate method for checking the set point of the engine. Review the required tools for the new method. If these tools are not available, you can use an alternative method for checking set point.
| Required Tools | ||
| Part Number | Part Name | Quantity |
| 9U-7400 | Multitach | 1 |
| | |
| Illustration 18 | g00300249 |
9U-7400 Multitach | |
You can use the 9U-7400 Multitach to check the set point. Refer to Special Instruction, SEHS7931 for instructions on using this tool group.
Alternate Method for Checking Set Point
| Required Tools | ||
| Part Number | Part Name | Quantity |
| 9U-7400 | Multitach | 1 |
| 8T-0500 | Continuity Tester | 1 |
If the set point is correct and the high idle rpm is within specifications, the fuel system operation of the engine is correct. The set point for the engine is determined by these factors:
- 20 rpm greater than full load rpm.
- The rpm upon contact between the rack stop collar and the torque spring or the stop bar.
- The rpm where the engine gets the maximum amount of fuel per stroke.
- The rpm where the engine has maximum horsepower output.
- The rpm where an increase in load on the engine puts the engine in a lug condition. A lug condition is where a small increase in load causes the engine speed to decrease.
Use the following procedure to check the set point.
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| Illustration 19 | g00343139 |
Circuit tester (installed) (1) Brass terminal screw (2) 8T-0500 Continuity Tester | |
Note: Refer to Special Instruction, SEHS7050, "Techniques for Loading Engines" for more information.
- Connect an accurate tachometer to the tachometer drive.
- Connect the clip end of the 8T-0500 Continuity Tester to the brass terminal screw (1) on the governor housing.
- Then, connect the other end of the tester to a place on the fuel system with a good ground connection.
- Start the engine.
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Personal injury can result from rotating and moving parts. Moving fan blades and moving parts will throw or cut any object or tool that falls or is pushed into them. Ensure that no one is working on, underneath or close to the machine before starting the engine. Ensure the area is free of personnel. |
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- With the engine at normal operating conditions, operate the engine at high idle.
- Record the rpm of the engine at high idle.
- Slowly add load to the engine until the circuit tester light shows a minimum light output.
This is the set point.
- Record the engine rpm at set point.
- Repeat 7 for several times in order to ensure that the reading is correct.
- Stop the engine.
- Compare the records from both Steps 6 and 8 with the information from the FUEL SETTING INFORMATION.
- If the set point is correct, the governor setting is adjusted correctly. If the set point is not correct, adjust the high idle rpm until you get the correct set point.
| NOTICE |
|---|
To help prevent engine damage, never exceed the high idle rpm. An overspeed can result in serious damage to the engine. The engine can be operated at high idle without damage, but the engine should never be allowed to exceed the high idle rpm. |