Series 50 – Section 2.34 Fuel Shutoff Valve for 1998 and Later Series 50G Engine With High Pressure Fuel System

Section 2.34
Fuel Shutoff Valve for 1998 and Later Series 50G Engine With High Pressure Fuel System

The fuel shutoff valve is typically mounted in the engine compartment. It must be no further than 24 inches away from the low pressure fuel regulator. The function of the valve is to shutoff fuel at the inlet of the IMPCO regulator. The valve is powered by an electric solenoid. The valve is normally closed and is available with either 12 volt or 24 volt solenoids. Electrical power to the solenoid is controlled by both DDEC and vehicle electrical systems. The DDEC ECM supplies a signal to open the valve when ignition is on and engine speed is above 60 RPM. The valve is closed when ignition is switched off, or when engine speed falls below 60 RPM or when an engine protection shutdown occurs. Vehicle systems typically tie power to the valve with the ignition switch and other safety systems such as fire suppression or methane (gas leakage) detection systems. The solenoid power is supplied through the vehicle wire harness. The gas inlet and outlet are female 1/2 inch NPTF connections. The shutoff valve comes with a mounting bracket attached. See Figure "Fuel Shutoff Valve for Series 50G Engine" .‪

Figure 1. Fuel Shutoff Valve for Series 50G Engine

Section 2.34.1
Replacement of the Fuel Shutoff Valve for the Series 50G Engine

The fuel shutoff valve is not serviceable and should be replaced as a unit. No adjustment is required. ‪

Section 2.34.2
Removal of the Fuel Shutoff Valve for the Series 50G Engine

Remove the fuel shutoff valve as follows:‪

1. Vent fuel system, refer to "2.43 Venting and Leak Checking Procedures for a Natural Gas Engine (Low Pressure System)" .
2. Disconnect fuel supply pipe at shutoff inlet.
3. Disconnect fuel pipe from shutoff outlet.
4. Disconnect electrical connector.
5. Remove two bolts attaching the shutoff valve bracket to its mounting bracket and remove shutoff valve and bracket assembly.

Section 2.34.3
Installation of the Fuel Shutoff Valve for the Series 50G Engine

Install the fuel shutoff valve as follows:‪

1. Install gas inlet and outlet fittings.
2. Position shutoff valve on mounting bracket.
3. Install mounting bolts.
4. Connect fuel outlet hose to outlet fitting.
5. Connect fuel supply pipe to inlet fitting.
6. Connect solenoid electrical connector to connector in vehicle wire harness.
7. Open manual fuel shutoff valves and crank engine to supply fuel.
8. Check for leaks, refer to "2.43.3 Leak Checking the Natural Gas Fuel System" .