outlet cavity. Since this is a continuous cycle and fuel is continually being forced into the outlet cavity, the fuel
flows from the outlet cavity into the fuel lines and through the engine fuel system under pressure.
The pressure relief valve relieves the discharge pressure by bypassing the fuel from the outlet side of the pump
to the inlet side when the discharge pressure reaches approximately 65 to 75 psi (448 to 517 kPa).
The fuel pump should maintain the fuel pressure at the fuel inlet manifold as shown in Engine Operating
Remove Fuel Pump
1. Disconnect the fuel lines from the inlet and outlet openings of the fuel pump.
2. Disconnect the drain tube, if used, from the fuel pump.
3. Remove the three pump attaching bolt and seal assemblies and withdraw the pump.
4. Check the drive coupling fork and, if broken or worn, replace it with a new coupling.
Disassemble Fuel Pump
With the fuel pump removed from the engine and mounted in holding fixture J 1508-10 as shown in Fig. 3, refer
to Fig. 1 and 5 and disassemble the pump as follows:
1. Remove the eight cover bolts and withdraw the pump cover from the pump body. Use care not to damage
the finished faces of the pump body and cover.
2. Withdraw the drive shaft, drive gear, and gear retaining ball as an assembly from the pump body.
Figure 3. Removing Fuel Pump Cover
3. Press the drive shaft just far enough to remove the steel locking ball. Then invert the shaft and gear
assembly and press the shaft from the gear. DO NOT misplace the steel ball. Do not press the squared end of
the shaft through the gear as slight score marks will damage the oil seal contact surf ace.
4. Remove the driven shaft and gear as an assembly from the pump body. DO NOT remove the gear from the
shaft. The driven gear and shaft are serviced only as an assembly.
5. Remove the relief valve plug and copper gasket.
6. Remove the valve spring, pin, and relief valve from the valve cavity in the pump body.
7. If the oil seals need replacing, remove them with oil seal remover J 1508-13 (Fig. 4). Clamp the pump body
in a bench vise and tap the end of the tool with a hammer to remove the outer and inner seals.