DD5 Medium Duty Engine Fuel System - Introduction - OEP61E

DD Medium Duty Engine - Introduction - OEP61E

Fuel System > 4.1 Components

HC Doser Supply

The HC doser feed line delivers fuel from the fuel filter module manifold to the inlet side of the HC doser block assembly. The fuel is dead headed against the fuel cut off valve until engine operation conditions require activation.

Fuel Injector

The fuel injector is a signal solenoid-operated injector with a 10 spray hole nozzle which can deliver a maximum injection pressure of 2,400 bar / 34810 psi.

Fuel Rail

The fuel rail incorporates the one high pressure rail feed line connection, 4 one time use high pressure fuel lines to fuel injectors, the fuel rail pressure sensor along with the pressure control valve.

Heat Isolator

The heat isolator is a protective sleeve which reduces temperature at the injector nozzle along with protecting the nozzle tip from damage. The sleeve also seals compression from entering the fuel system. This part is a one time use part.

High Pressure Pump (HPP) Return

The high pressure pump (HPP) return line transfers the unused low pressure fuel supply for the high pressure pumping element head along with QCV unused fuel back to the fuel filter module return circuit.

High Pressure Pump (HPP) Inlet

The high pressure pump inlet line transfers low pressure (water separated) final filtered fuel to the high pressure fuel pump. The high pressure pump side connection point contains a disk shaped pressed in filter for extra protection of the high pressure system.

Injector O-rings (seals)

The injector O-rings seals prevent fuel from entering into the cylinder head contaminating the lubrication system. The seals are one time use parts.

Injector Backflow Line

The injector back flow is a single line that connects to the cylinder head and connects to a pressure control valve.

Injector Backflow Control Valve

The injector back flow pressure control valve regulates pressure at 87 psi / 6 bar of pressure on the backflow circuit.

Injector Feed Line

The injector feed line transfers the high pressure fuel supply from the fuel rail into individual injectors. There are 4 one-time use injector feed lines on this model engine.

Injector Crab (injector nozzle clamp)

The injector nozzle clamp (crab) secures the injector to the cylinder head while maintaining the proper clamp load to keep compression gas from leaking into the fuel injection system.

Low Pressure Pump (LPP) Outlet

The low pressure pump (LPP) outlet transfers low pressure fuel from the low pressure pump to the fuel filter module within a pressure protection circuit.

Low Pressure Pump (LPP) Inlet

The low pressure pump inlet transfers pre-filtered fuel to the low pressure pump.

Fuel Main Filter

The main filter is where the smaller particles of dirt ( >2 micron ) are filtered. The fuel is led for this purpose through an appropriately constructed filter element. The main filter is an outside-in style filter.

Mixed Backflow

The mixed backflow is from the pressure control valve and the injector back flow circuit connecting with the fuel return circuit within the fuel filter module.

Fuel Prefilter

The pre-filter is where large dirt particles ( >100 micron ) are filtered out of the fuel before entry into the low pressure fuel pump. The pre-filter is an outside-in style filter.

PCV Return (pressure control valve)

The pressure control valve reduces the stored rail pressure. This valve is actively used during normal engine operation. During the initial the key off state leakage will be present. This is an important fact to understand during diagnostics because leakage will be normal until the mechanical spring in the valve closes at 300 bar / 4350 psi. Below 300 bar / 4350 psi there should be no leakage.

Service Port

The service port is on the suction ( draw ) side of the low pressure system. This port can be used for priming the system with a max of 95 psi / 6.6 bar of pressure. The port will also be used for fuel system diagnostics.

Vehicle Connector

The vehicle connector incorporates a shut off valve with a positive opening. The insertion of the proper fitting moves the valve forward. When the fitting is removed the valve closes preventing fuel drainage from the filter module.