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The compuvalve contains the metering valve and computer for the system. See Figure 24878 . ‪

1. BAP Sensor and Filter ‪

6. Main Wire Harness ‪

2. High Flow Injectors ‪

7. FRT Sensor ‪

3. MAP Barb ‪

8. Low Flow Injectors ‪

4. Inlet Port ‪

9. 10 AMP Fuse ‪

5. Outlet Port ‪

10. 3 AMP Fuse ‪

Compuvalve for the Series 50G Engine

Regulated gas from the GFI regulator, enters the compuvalve through the inlet port and flows through the fuel rail. The flow is then regulated by 7 injectors that are computer controlled and operated by electronic solenoids. There are 5 high flow injectors for on/off operation for major flow changes and 2 low flow injectors that are pulse width modulated for flow trimming. There are four sensors in the metering valve, and two additional engine mounted sensors that the computer uses to calculate open loop fueling requirements. The sensors located in the metering valve are: Manifold Absolute Pressure (MAP), Barometric Absolute Pressure (BAP), Fuel Absolute Pressure (FAP) and Fuel Regulated Temperature (FRT). The engine mounted sensors are the Inlet Air Temperature (IAT), and Oil Temperature Sensor (OTS). The regulated gas flow is then released through the outlet port to the gas mixing unit located in the air intake system upstream of the engine throttle. ‪

The computer controls fuel flow. The computer section consists of a 2 board computer module inside the electronics cavity of the metering valve. For calibration and adaptive memory, the ECM uses SRAM (Static Random Access Memory). Program memory is stored in ROM (Read Only Memory). The memory is non-volatile and is neither reset nor lost when battery voltage is removed. ‪

The software is responsible for calculations, based on calibration and sensor input, that result in computer commands that adjust fuel flow. The calibrations are programmable. ‪

Replacement of the GFI Compuvalve for the Series 50G Engine

The GFI compuvalve is non-serviceable and should be replaced as a unit. No adjustment is required. ‪

Removal of Compuvalve for the Series 50G Engine

Prior to removal of the compuvalve, the fuel system must be vented. Refer to Section and refer to Section . ‪


To avoid injury from the explosion of natural gas, the engine must be kept in a well ventilated area away from open flames, sparks, and electrical resistance (heating) coils.


When disconnecting the GFI compuvalve wire connectors, all power, including the ignition and the batteries, must be off. If this is not done, the injector drivers may be damaged. ‪

After the fuel system has been properly vented, remove the compuvalve as follows: ‪

  1. Turn off ignition and disconnect batteries by turning off the battery switch or removing the ground cable from the battery.
  2. Disconnect all wire harness connections at the compuvalve.
  3. Disconnect gas inlet hose at the compuvalve.
  4. Disconnect the gas outlet hose.
  5. Disconnect map sensor hose assembly at the compuvalve.
  6. Remove bolts attaching the compuvalve to its mounting bracket.
Inspection of Compuvalve for the Series 50G Engine

Inspection of the compuvalve is not required. ‪

Installation of Compuvalve for the Series 50G Engine

Install the compuvalve as follows: ‪


Make sure that no dirt or debris is allowed to enter unit during installation. Tightly cap or cover all open ports and openings. Do not remove factory caps until time to connect hoses. ‪

  1. Mount compuvalve in its bracket and install attaching bolts.
  2. Connect map sensor hose.
  3. Connect gas outlet hose.
  4. Connect gas inlet hose.
  5. Connect wiring harness.
  6. Turn on battery switch or reconnect battery ground cable.


    To avoid injury from an explosion of natural gas, the following precautions must be taken:

    • Do not smoke when installing or servicing the engine or fuel system.
    • Installation or servicing of natural gas equipment must only be conducted in well ventilated, natural gas-compatible areas. Do not install or service equipment in an enclosed area where ignition sources are present without first ensuring that an undetected gas leak may be safely vented without being ignited.
    • Bleed natural gas lines before installing or servicing any component connected to the fuel lines.
    • Natural gas fuel systems are pressurized. Relieve pressure from any fuel system component prior to installation or service of that component.
    • Use a combustible-gas detector. Liquefied natural gas (LNG) is odorless and cannot be detected by smell. Compressed Natural gas (CNG) may be odorless and may not be detected by smell.
    • Equipment fuel systems are the responsibility of the Original Equipment Manufacturer (OEM). Equipment fuel system guidelines must be closely adhered to when installing or servicing equipment. Refer to OEM guidelines specifying which maintenance procedures require venting of fuel lines and fuel tanks.
    • LNG systems are pressurized and contain extremely cold (-260 F [-162 C]) fluids. Contact the fuel supplier or OEM for LNG safety requirements. Contact with LNG may cause personal injury (freezing).
    • Vent systems on the equipment should be ducted to a safe area whenever equipment is in an enclosed area.
  7. Start engine and check for leaks; refer to Section .