Volvo Trucks North AmericaDateGroupNo.PageService Bulletin
2019 Volvo Impact EPC+ Service Repair Manual Download
Fuel is drawn up the fuel lines by the supply pump (1)through the pickup tube in the fuel tank (2) in through theEngine Electronic Control Unit (EECU) cooling coil (3),and into the fuel filter housing (4). The fuel filter housingis equipped with a pre-filter (5) and a water separator(6), where fuel is filtered through the primary filter thatseparates any water from the fuel.
The supply pump (1) forces the fuel into the fuel filterhousing through the main filter (7) to a cylinder headlongitudinal fuel gallery (8). This channel supplies eachunit injector (9) with pressurized fuel by a circular groovearound each unit injector in the cylinder head. Theoverflow valve (10) controls the fuel supply pressure tothe unit injectors.
The return fuel from the overflow valve (10) is returnedback to the fuel filter housing and is mixed with the fuelfrom the fuel tank in a channel within the fuel filter housing(4).
Supply Pump Valves
Two valves are located in the supply pump (1).The safety valve (11) allows fuel to flow back to thesuction side when the pressure becomes too high, e.g., ifthe fuel filter is blocked or is too restricted. The non-returnvalve (12) opens when hand-priming is used.
Automatic Bleeding
If air gets into the system, it is bled when the enginestarts. During bleeding, the air is pressed out through thefuel filter housing over to the fuel tank through the returnline (25). Bleeding for the filter replacement is controlledby valves (17) and (23).
Water Drainage
Draining water from the water separator (5) requires thefollowing:•The sensor (14) in the water separator indicates waterin the fuel bowl.•The engine is not running.•The ignition key is in the ON position.•The parking brake is applied.When the switch (15) is depressed (located in the cabinstrument panel), the drain valve (16) opens for about15 seconds and drains the water. If additional drainageis needed, wait 6 minutes before repeating because thefunction is on a timer.
Manual Hand Pump
The manual hand pump (11) is located on the fuel filterhousing and is used to pump fuel (when the engine is notrunning) after the fuel system has been drained for repair,etc. The non-return valve (22) for the hand-priming pumpis also located in the fuel filter housing.
