Usage:
3406B Truck Engines Equipped With New Scroll Fuel System
Care must be taken during installation of individual 2W3413 Fuel Injection Pumps on the above truck engines. If the pump is not installed in the housing correctly, it will not allow full rack travel in both directions. This can affect engine performance and result in misfire and/or rough running.
Fuel injection pump installation must always be done carefully, especially in titled (non-vertical) engine installations. When the pump is installed in the engine, gravity can cause the steel segment gear to rotate slightly. If the gear rotates during installation, the alignment of the gear segment and rack will not be correct and will prevent full rack travel in both directions.
The following procedure and checks can be used to insure correct installation and operation of any number of individual replacement pumps on most truck engines.
Procedure To Install A Replacement Fuel Injection Pump
1. Rotate the fuel pump camshaft so the replacement fuel injection pump will be installed on the base circle, not on the lobe of the fuel pump camshaft.
2. Remove or activate the shutoff solenoid.
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- a. On truck engines, the low idle adjustment must be backed out to eliminate interference with full rack travel caused by the shutoff detent mechanism.
NOTE: To check the installation of a replacement pump, it is necessary to have full rack travel in both directions. Use the above steps (as needed) to position the pump and have full rack travel in both directions. The actual zero location of the timing pin and rack are not used to check the installation of replacement pumps.
3. Remove the cover (rack position indicator) and plug (rack centering pin) and install the 6V4186 Timing Pin as shown in Illustration 1.
Illustration 1. Fuel rack and timing pin.
4. Raise the timing pin and move the rack to the full load position. Use finger pressure to be sure the rack is at full rack travel (beyond full load position).
5. If the fuel injection pump installation is correct, when the timing pin is lowered it will be on the rack as shown in Illustration 2.
Illustration 2. Correct installation in full load position.
6. If the fuel injection pump installation is NOT correct, the timing pin position will be approximately 1.91 mm (.075 ") toward the slot for each tooth position out of alignment (see Illustration 3). This will reduce fuel rack travel, even though it may not affect the rack setting, because of additional rack travel at static conditions.
Illustration 3. Incorrect installation, full load position restricted by less than full rack travel.
7. Raise the timing pin and move the rack to the no load (fuel off) position.
8. If the fuel injection pump installation is correct, when the timing pin is lowered it will be in the timing slot, less than 1.91 mm (.075 ") from the rear face of the slot as shown in Illustration 4.
Illustration 4. Correct Installation at no load (fuel off) position.
9. If the fuel injection pump installation is NOT correct, the timing pin position will be more than 1.91 mm (.075 ") from the rear face of the timing slot in the rack (see Illustration 5).
Illustration 5. Incorrect installation, fuel shutoff position restricted by less than full rack travel.
10. When all fuel injection replacement pumps are installed correctly, complete the assembly and adjustments given in the Service Manual.
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If one or more of the fuel injection pumps have been installed wrong, it is possible for the engine to run out of control when started. When any of the fuel injection pumps have been removed and installed with the fuel injection pump housing on the engine, take the precautions (steps) given in the Service Manual to stop the engine if it starts to overspeed (run out of control).
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