ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 006-999   Injectors and Fuel Lines – Overview

WARNING  Fuel is flammable. Keep all cigarettes, flames, pilot lights, arcing equipment, and switches out of the work area and areas sharing ventilation to reduce the possibility of severe personal injury or death when working on the fuel system.

Injectors used in the ISC and ISL engines have hole type nozzles. High pressure fuel flows into the side of the injector and causes the needle to lift and fuel to be injected. The clearances in the nozzle bore are extremely small and any sort of dirt or contaminants will cause the injector needle valve to stick. This is why it is important to clean the area around any fuel connection before servicing it. Also, cap or cover any open fuel connections before a fuel system repair is performed.

High pressure fuel is supplied to the injector (1) from the fuel pump via an injector supply line (2) and a fuel connector (3). The end ferrule on the injector supply line pushes against the fuel connector when the fuel line nut is torqued in the cylinder head. This force provides the sealing pressure between both the injector supply line to the fuel connector and the connector to the injector.

The torque on this line is critical. If the nut is under torqued, the surfaces will not seal and a high pressure fuel leak will result. If the nut is over torqued, the connector and injector will deform and also cause a high pressure leak. The leak may result in an injector misfire and low power.

Always lubricate the threads of the high pressure line nuts with engine oil before tightening. Always make sure the proper torque is used on the high pressure line nuts.

The fuel connector contains an edge filter that breaks up small contaminants that enter the fuel system. The edge filter uses the pulsating high pressure to break up most particles so they are small enough to pass through the injector.

NOTE: The edge filters are not a substitute for cleaning and covering all fuel system connections during repair. Edge filters are not a substitute for maintaining the recommended engine mounted fuel filter.

The fuel filter is a spin-on type.

Fuel flows around the outside of the filter and back up through the middle. The filtering media is a 10 micron Stratapore™ design for efficient debris removal. The filter also strips the water and collects it at the bottom of the filter to be drained daily.

The ISC and ISL lift pump will run for 30 seconds after the key is switched on to assist with fuel priming. The lift pump will run during cranking and while the engine is running until the 30 seconds has lapsed. The lift pump will shut off anytime the key is switched “OFF”. The 30 second timer is reset after each key switch cycle and ECM power down.

Once the engine is started, additional fuel is drawn through the lift pump head via the gear pump. A valve in the head opens when the gear pump requires more flow than the lift pump can provide or when the lift pump is shut off.

WARNING  Fuel is flammable. Keep all cigarettes, flames, pilot lights, arcing equipment, and switches out of the work area and areas sharing ventilation to reduce the possibility of severe personal injury or death when working on the fuel system.

High-pressure common rail fuel systems use solenoid-actuated injectors. High-pressure fuel flows into the side of the injector. When the solenoid is activated, an internal needle lifts and fuel is injected. The clearances in the nozzle bore are extremely small and any dirt or contaminants can cause the injector to stick. This is why it is important to clean around all fuel connections before servicing the fuel system. Also, cap or cover any open fuel connections before a fuel system repair is performed.

CAUTION  To reduce the possibility of engine damage, always use the proper torque value and the proper torquing sequence on the high-pressure line nuts.

High-pressure fuel is supplied to the injector from the fuel rail by an injector supply line and a fuel connector. The fuel connector pushes against the injector body when the fuel connector nut is tightened. The injector supply line is then connected to the fuel connector.

The torque and sequence for this joint is critical. If the nut or line is undertightened, the surfaces may not seal and a high-pressure fuel leak will result. If the nut is overtightened, the connector and injector will deform and can cause a high-pressure fuel leak. This leak will be inside the head and will not be visible. The result will be a fault code, low power, or no-start.

If the injector is not fully seated prior to the installation of the high-pressure connector, the joint will not seal.

The fuel connector contains an edge filter that breaks up small contaminants that enter the fuel system.

The edge filters are not a substitute for cleaning and covering all fuel system connections during repair.

Be sure to cap or cover all fuel fittings and ports.

All injectors feed into a common return drilling contained within the cylinder head. Any excess fuel is returned to the tank via this drilling and return line attached to the rear of the cylinder head. A back-pressure valve is located on the back of the cylinder head where the drain line attaches.

The electronic control module (ECM) controls the fueling and timing of the engine by actuating the injector solenoids. An electronic pulse is sent to the solenoids to lift the needle and start the injection event. By electronically controlling the injectors, there is a more precise and accurate control of fueling quantity and timing. Also, multiple injection events can be achieved by electronically controlling the injectors.

The engines covered in this manual require original equipment manufacturers (OEM’s) to mount a 10-micron suction filter prior to the OEM fuel supply connection at the rear of the engine block. The 10-micron filter performs water stripping and includes a water-in-fuel sensor. The water-in-fuel sensor must be installed. If not, a fault code warning lamp will be active.

The engines covered in this manual also include a 2-micron pressure-side fuel filter. The pressure-side filter will be located downstream of the gear pump before the high-pressure fuel pump inlet. If a water-in-fuel fault is experienced, drain the water stripping filter and replace the pressure side fuel filter.