Fuel Pump Service Operation On-Vehicle
Operations which can be performed individually without removing the pump from the engine are as follows:
• Cover seal replacements
• Guide stud seal replacements
• Throttle shaft seal replacements
• Governor weight retainer ring checking procedure
• Min-Max governor service
The procedure that follows include disassembly, various seal replacements, installation of the pellethane governor
weight retainer ring, and a bench leak test.
Mounting in Holding Fixture Mount the pump in the holding fixture, Tool #J-29692B (BT 8046). Always use the fixture to avoid damage to the pump. NEVER MOUNT THE PUMP DIRECTLY IN A VISE. (Figure 4-83).
See Figure 4-84. Rotate the throttle lever to the low idle position and install Tool J-29601 over the throttle shaft with slots of tool engaging pin. Put the spring clip over the throttle shaft advance cam and tighten the wing nut. Without loosening the wing nut, pull the tool off the shaft. (This provides the proper alignment on reassembly).
Unscrew the three governor cover hold down screws and remove the governor control cover and cover gasket. (Figure 4-85).
Examine the electric shut off solenoids (Figure 4-86) and the housing pressure cold advance solenoid if so equipped, for damage or debris. Clean the solenoids with compressed air. Solenoid plungers should move freely in their bores.
Remove the drive pin from the throttle shaft using the appropriate drift punch. (Figure 4-87).
LIGHT LOAD ADVANCE ROCKER ARM AND FACE CAM
All mechanical light load advance pumps are equipped with a rocker arm, which contact the servo advance plunger at one end and a face cam which is located on the throttle shaft at the other end. (Figure 4-88).
Pry off the retaining rings from the rocker lever pin and discard the rings. (Figure 4-89).
Push out the pin and remove the lever assembly. (Figure 4-90).
Face Cam Removal
Loosen the face cam screw, using a 5/32″ hex bit, or #27 Torx bit. The screw must be fully withdrawn to allow for removal of the face cam. (Figure 4-91).
Using a 7/16″ open end wrench or a V \” Allen, loosen and withdraw the guide stud. (Figure 4-92).
Observe position of metering valve spring over the top of the guide stud. This position must be exactly duplicated during reassembly. Remove guide stud and washer.
Governor Spring Components
While holding the Min-Max assembly between the thumb and forefinger, rotate the throttle and lift out the governor spring components. (Figure 4-93).
Now, simply pull the throttle shaft assembly through the housing. Remove the mylar washer and O ring seals from the throttle shaft. (Figure 4-94).
While depressing the metering valve assembly raise the linkage hook from the metering valve arm. (Figure 4-95).
Governor Arm and Linkage (Late Model)
The governor arm and linkage assembly may be removed as a single unit. (Figure 4-96).
Remove the metering valve assembly. (Figure 4-97).
Vent Wire Assembly
Remove the vent wire screw assembly, using a 1/8″ Allen wrench. (Figure 4-98).
End Cap Locking Screw
Loosen and remove the transfer pump end cap locking screw, plate and seal from the hydraulic head. (Figure 4-99).
Transfer Pump End Cap
In a counterclockwise direction, loosen and remove the transfer pump end cap assembly, using the appropriate end wrench. (Stanadyne Tool #20548, Figure 4-100).
See Figure 4-101. With the end cap assembly removed, remove the transfer pump regulator assembly.
Transfer Pump Blades and Liner
See Figure 4-102. If the liner and blades fall out, note on which side the “ potmark” is located on the liner. Also identify which slots in the rotor each blade comes from and mark them with Dykem stain, Stanadyne Part #18836.
End Cap Seal
Remove the transfer pump end cap seal. (Figure 4-103).
Loosen the head locking screws and remove one screw. (Figure 4-104, left).
Carefully invert the pump and holding fixture in the vise, and remove the head locating screw. (Figure 4-104, right).