FRAME AS 1351040 - Caterpillar

Operation
Fuel for the diesel engine is drawn from the fuel supply tank (8) by the fuel transfer pump (13). Later engines have a bypass valve (15) in the transfer pump to bypass fuel at pressures above 50 2 PSI (3,52 0,01 kg/cm2).The fuel transfer pump delivers fuel through line (12) to the fuel filter housing (4) and forces fuel through the filter elements. A bypass valve (7) located in the fuel filter housing maintains approximately 15 PSI (1,05 kg/cm2) of pressure in the filter housing. Excess fuel supplied by the transfer pump is returned to the supply tank through line (10).Fuel passing through the fuel filters is directed to the fuel manifold located in the fuel pump housing by line (6). The fuel manifold distributes the fuel to the individual fuel injection pumps.
FUEL SYSTEM (SCHEMATIC) 1 Fuel injection pump housing.2 Injection line.3 Injection valve.4 Fuel filter housing.5 Fuel pressure gauge.6 Injection pump supply line.7 Bypass valve.8 Fuel supply tank.9 Bleed line.10 Return line.11 Vent lines from bleed valves.12 Fuel supply line.13 Fuel transfer pump.14 Priming pump.15 Transfer pump bypass valve (Later engines).The cam-actuated injection pumps force a measured quantity of fuel under high pressure through injection lines (2) to the injection valves (3). The single orifice injection valves spray fuel into the combustion chamber where it is burned.A hand-operated fuel priming pump (14) is used, when necessary, to assure that the fuel in the fuel manifold is under pressure at the time of starting.
FUEL LINES (D399 Engine Illustrated)
6-Injection pump supply line. 9-Bleed line. 10-Return line. 11-Vent lines (Two on later engines). 12-Fuel supply line.Air is bled from the fuel system through a single bleeder valve or earlier engines. Later engines have a bleeder valve on the unfiltered side as well as filtered fuel side of the element. When the valves are open, any air in the fuel lines, fuel filter housing, or bleeder manifold is discharged through the vent lines (11). For priming and air bleeding procedures, see the covering topic in the LUBRICATION AND MAINTENANCE PROCEEDURES of the OPERATION GUIDE.A pressure gauge (5) indicates the fuel pressure on the supply side of the fuel injection pump housing.Lack of pressure on the gauge indicates difficulty in the supply side of the system. This could be caused by an empty diesel fuel tank, closed shutoff valve at the tank, clogged filters, dirt under the bypass valves, open vent valve, a faulty transfer pump or gauge.Air in the system or water in the fuel can also be responsible for the engine firing irregularly or failing to start.If, after eliminating the above possibilities, there still seems to be something wrong with the fuel system, check the injection side of the system. Fuel injection pumps and fuel injection valves can be checked as described in the topic, FUEL INJECTION EQUIPMENT.Many times the fuel system is blamed when the fault lies elsewhere. A smoky exhaust may be caused by faulty fuel injection valves. But it can also be caused by dirty