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The IMPCO low pressure regulator is mounted to the air inlet elbow at the front left side of the engine. The gas inlet connection is a 1/4in. NPTF pipe thread and is connected through a special natural gas compatible No. 8 hose to the low pressure DDEC controlled fuel shutoff valve. The gas outlet connection is a oneinch NPTF pipe thread and is mated to the inlet of the PSV through a special tube connector. The regulator is heated by engine coolant. The regulator outlet fuel pressure is balanced to turbo boost pressure at the mixer inlet. This pressure is communicated to the regulator through a No. 8 hose that connects to a 1/8in. NPTF pipe thread hole in the regulator cover and to a 1/4in. pipe thread connection in the top of the mixer housing. ‪

IMPCO is a registered trademark of IMPCO Technologies, Inc. ‪

The purpose of the regulator is to provide a controlled flow of natural gas to maintain regulator outlet fuel pressure at a pressure nearly equal to air pressure (turbo boost) at the inlet to the mixer. Gas enters the regulator at a pressure of approximately 110 PSI. See Figure 34515 . ‪

1. Fuel Temperature Sensor ‪

6. Low Pressure Regulator ‪

2. PSV ‪

7. Air Temperature Sensor ‪

3. Fuel Mixer ‪

8. Fuel Pressure Sensor ‪

4. Throttle ‪

9. Fuel Inlet Tee-Fitting ‪

5. Air Inlet Elbow ‪

60G Throttle with Integrated Actuator

Replacement of the Low Pressure Regulator for the Series 60G Engine

The low pressure fuel regulator is not serviceable and should be replaced as a unit. No adjustment is required. ‪

Removal of the Low Pressure Regulator for the Series 60G Engine

Remove the low pressure fuel regulator as follows: ‪


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.

  1. Vent fuel system, refer to section .
  2. Disconnect fuel supply hose at the regulator.
  3. Disconnect fuel pressure sensor from engine sensor wiring harness.
  4. Drain coolant.
  5. Disconnect coolant supply and return hoses at regulator.
  6. Disconnect air balance hose at regulator cover.
  7. Remove two M6 regulator to air inlet elbow mounting bolts. Support regulator to avoid cocking the connector tube in the PSV and possibly damaging the PSV gas inlet bore.
  8. Slide regulator rearward to disengage outlet connector tube from the PSV.
  9. Remove gas inlet tee, fuel pressure sensor, coolant inlet fittings, coolant outlet fittings, balance hose fitting, outlet connector tube and O-rings for reuse.

Installation of the Low Pressure Regulator for the Series 60G Engine

Install the low pressure fuel regulator as follows: ‪


Use caution when installing hoses to avoid twisting or kinking the hose. This could result in increased flow restriction and affect engine performance. ‪


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.
  1. Install gas inlet tee, fuel pressure sensor, coolant inlet fittings, coolant outlet fittings, balance hose fitting, outlet connector tube and O-rings.
  2. Lubricate connector O-rings.
  3. Position regulator on air inlet elbow with outlet connector aligned with bore in PSV. Slide regulator forward engaging outlet tube in PSV until regulator mounting bolt holes are aligned.
  4. Install two M6 mounting bolts.
  5. Connect fuel supply hose.
  6. Connect coolant supply and return hoses.
  7. Refill with coolant.
  8. Connect air balance hose.
  9. Connect fuel pressure sensor to engine sensor wiring harness.
  10. Clear AFR learn table using DDR.
  11. Start engine and check hoses and fitting for leaks. Refer to section .