Usage:
Fuel Transfer Pump
The fuel transfer pump delivers the fuel from the main supply tank, through the fuel filter to the fuel injection pump housing. The fuel transfer pump mounts on the oil pump housing, and is driven by the oil pump drive shaft. The fuel transfer pump can be removed and installed when the oil pump is either mounted on the engine or removed from it.
Removal and Installation
If the oil pump is mounted on the engine, drain the fuel filter housing and disconnect the fuel lines at fuel transfer pump (2).
Remove fuel transfer pump (2) from oil pump (3).
PREPARING TO REMOVE THE FUEL TRANSFER PUMP
1-Bolts (seven). 2-Fuel transfer pump. 3-Oil pump.
FUEL TRANSFER PUMP REMOVAL
Disassembly and Assembly
The shaft supporting idler gear (5) is pressed into the pump body and can be removed.
Replace the bearings in seat assembly (9) and transfer pump body (1) if necessary. Install the bearings with the tapered edge toward the seals.
COVER REMOVAL
1-Transfer pump body. 2-Cover.
DISASSEMBLING PUMP BODY
3-O-ring seal. 4-Drive gear. 5-Idler gear. 6-Lock ring. 7-Key.
PUMP DRIVE SHAFT DISASSEMBLY
8-Snap ring. 9-Retainer. 10-Seal. 11-Seal ring. 12-Seal. 13-Bearing. 14-Seal seat. 15-Shaft.
Replace any worn or damaged seals and install in reverse order of removal.
Fuel Priming Pump
The wobble-type priming pump is located on top of the front accessory drive housing. The needle valve for bleeding the entire fuel system is on top of the fuel filter housing. When bleeding the system, the glass window in the housing enables the operator to see when the fuel is free of air bubbles.
For instructions on priming the engine, consult the Lubrication and Maintenance Guide.
Removal and Installation
On D379 and D398 Engines disconnect oil line from elbow at (3).
PREPARING TO REMOVE FUEL PRIMING PUMP (D399 Engine Illustrated)
1-Priming pump. 2-Fuel lines. 3-Oil line elbow. 4-Bolts (four). 5-Rod.
Disassembly
PREPARING TO DISASSEMBLE FUEL PRIMING PUMP
1-Front lid assembly. 2-Bolts. 3-Plug.
DISASSEMBLY OF FUEL PRIMING PUMP
1-Front lid assembly. 4-Outlet deck. 5-Cylinder.
The inlet deck can also be removed from the cylinder.
NOTE: If it is necessary to prime the pump, remove priming plug (3), pour fuel in the pump and install the plug.
DISASSEMBLY OF LID ASSEMBLY
6-Lever. 7-Nut. 8-Gland. 9-Wing and shaft. 10-Lid.
Replace the packing in lid (10) if necessary.
Assembly
PRIMING PUMP ASSEMBLY
1-Dowels. 2-Outlet deck. 3-Outlet port. 4-Rear lid. 5-Inlet deck. 6-Plungers.
Assemble in reverse order of disassembly. Inlet deck (5) and outlet deck (2) must be replaced in their original position, with valve plungers (6) toward outlet port (3). The inlet and outlet decks are held in place by two dowels (1) in rear lid (4).
The end clearance of the pump is controlled by adding or removing gaskets between the pump cylinder and the front lid.
Fuel Filter
Removal and Installation
Drain the fuel from the fuel filter housing.
Disconnect the injection pump supply line (4) at the left end of fuel filter housing (8). D399 Engines have a fuel supply line connection on each housing.
On D398 and D379 Engines, disconnect the fuel pressure gauge line from location of plug (9) and lift off the filter housing.
DISCONNECTING FUEL LINES (Top Rear View of Fuel Filter Housing)
1-Vent tube. 2-Fuel supply line. 3-Fuel return line. 4-Injection pump supply line. 5-Bleed line.
PREPARING TO REMOVE FUEL FILTER HOUSING
6-Tube (D399 Engines only). 7-Bolts (four). 8-Filter housing. 9-Plug.
PREPARING TO REMOVE SECOND FUEL FILTER HOUSING (D399 Engine only)
10-Bolts (four). 11-Second filter housing.
Replace any damaged parts and install in reverse order of removal.
Disassembly and Assembly
Remove filter elements (3) from either end of the fuel filter housing.
NOTE: On D399 Engines the front filter has a cover in place of the bypass housing to remove.
The spring from the right end cover can be replaced if necessary.
Replace the gaskets and seal, if damaged.
FILTER DISASSEMBLY
1-Cover. 2-Bypass valve housing. 3-Filter elements (six each housing).
Fuel Bypass Valve
The bypass valve regulates the pressure of the fuel to the fuel injection pumps, because the transfer pump normally pumps more fuel than the engine can use.
When the oversupply of fuel builds up to a pressure that exceeds the spring force on the bypass valve plunger, the valve will open to regulate the pressure of the fuel to the fuel injection pumps. The fuel that passes through the open bypass valve returns to the fuel supply tank.
A sticking plunger can cause damaging high fuel pressure, or not enough fuel pressure to operate the engine.
Removal and Installation
It is not necessary to remove the bypass valve housing from the fuel filter housing to remove the bypass valve spring and plunger.
REMOVING BYPASS VALVE
1-Spring. 2-Plunger.
Remove the cover which bolts to the right end of the bypass valve housing.
Inspect the plunger and plunger seat for burrs, foreign material, and seat finish. Clean if necessary.
Install in reverse order of removal making sure the spring (1) and plunger (2) are seated properly.