Learn about your LTG - Fuel System

The fuel system in the LTG is a sophisticated electronic returnless on-demand design, which eliminates the need to return hot fuel from the engine back to the fuel tank. This design reduces internal fuel tank temperatures, resulting in lower evaporative emissions.

Key Components:

1. Fuel Pump:

   • An electric turbine-style fuel pump is located inside the primary fuel tank fuel pump module. This pump supplies fuel through the fuel feed pipe to the high-pressure fuel pump.

   • The fuel pump is controlled by the fuel pump flow control module, which receives commands from the engine control module (ECM) via a GMLAN serial data message.

2. High-Pressure Fuel Pump:

   • Receives fuel from the primary fuel tank fuel pump and supplies it to a variable-pressure fuel rail.

   • The high-pressure fuel pump's operation, including fuel pressure, injection timing, and duration, is controlled by the ECM.

3. Fuel Injectors:

   • Precision multi-hole fuel injectors deliver fuel directly into the combustion chamber at high pressure.

   • The ECM controls the operation of fuel injectors based on engine parameters to optimize combustion.

4. Fuel Tank:

   • Stores the vehicle's fuel supply and is located in the rear of the vehicle.

   • The fuel tank is made of high-density polyethylene and features a saddle configuration to accommodate a driveshaft through the center area.

5. Fuel Pressure Sensor:

   • Monitors fuel pressure within the system and provides feedback to the ECM for closed-loop fuel pressure control.

   • The fuel pressure sensor is located on the fuel feed line forward of the fuel tank.

6. Fuel Pump Flow Control Module:

   • Receives desired fuel pressure commands from the ECM and controls the fuel pump's operation to achieve the desired pressure.

   • Uses a PWM (Pulse Width Modulation) signal to vary the fuel pump's speed and maintain fuel pressure.

7. Fuel Level Sensor:

   • Determines the fuel level in the tank using a float and wire float arm.

   • Sends fuel level information to the ECM via the serial data circuit for display on the instrument panel cluster (IPC).

8. Fuel Rail Assembly:

   • Attaches to the cylinder head and distributes high-pressure fuel to the fuel injectors.

   • Includes the fuel injectors and fuel rail pressure sensor.

Fuel System Operation:

• The fuel pump within the primary fuel tank fuel pump module supplies fuel to the high-pressure fuel pump.

• The high-pressure fuel pump delivers fuel to the variable-pressure fuel rail.

• Fuel injectors controlled by the ECM spray fuel directly into the combustion chamber based on precise timing and duration commands from the ECM.

• The fuel pressure sensor provides feedback to the ECM for closed-loop fuel pressure control, ensuring optimal engine performance and efficiency.

Fuel Metering Modes of Operation:

• The ECM adjusts fuel delivery based on various engine parameters and sensor inputs to achieve optimal air/fuel ratios under different operating conditions (starting mode, clear flood mode, run mode, acceleration mode, deceleration mode, battery voltage correction mode, fuel cutoff mode).

• The ECM continuously monitors fuel trim values (short-term and long-term) based on feedback from the heated oxygen sensor (HO2S) to regulate fuel delivery for optimal driveability, fuel economy, and emission control.

The system's closed-loop operation and diagnostic capabilities ensure reliable operation and compliance with emissions regulations.