STARTING MOTOR GP-AIR 4W5105 - Caterpillar

Note: Callouts (7), (8), (12), (13), and (14) are part of the OEM system.The engine is shipped with a dual gaseous fuel arrangement (Natural gas/Field gas + Propane fuel train). The arrangement has two separate pressure regulators and fuel systems as shown in Illustration 1. This dual fuel system is only suitable with propane as the secondary fuel. No other fuel is acceptable for use with the secondary fuel train.A propane gas emission adjustment screw (5) is placed in between the propane gas regulator (6) and the carburetor (17). The propane gas emission adjustment screw is used to adjust the Air/Fuel ratio for the propane.ReferenceRefer to Special Instructions, REHS9280, "Air/Fuel Ratio Setup for Certified G3306B Generator Set Engines" for the Air/Fuel ratio setup instructions.Note: The shipped factory engine configuration cannot switch between the different fuels automatically. As shipped, the engine must be shut down and the fuels switched manually.The following guidelines are for automatic switching between the primary (natural gas/field gas) and secondary (propane) fuels. The engine software is programmed to allow for an automatic switch in ignition timing based. The customer can set up a system that allows for automatic switching between fuels using OEM parts similar to the parts listed in Illustration 1. The engine software allows for an automatic switch in ignition timing based on the output of the pressure switch (14). The pressure switch is located upstream of the natural gas solenoid. The pressure switch is customer provided and the specifications are available in Special Instructions, REHS9280, "Air/Fuel Ratio Setup for Certified G3306B Generator Set Engines". Before automatic switching of the fuel is permitted, complete "Part C" of Special Instructions, REHS9280 to ensure emissions compliance. Failure to do so will lead to higher emissions and could make the engine out of compliance.In this system, the primary fuel has a lower British Thermal Unit (BTU) than the secondary fuel. Dual regulator systems can transfer between the two different fuel supplies while under load. Do not move the fuel regulators from the factory mounting positions. Any increase in the fuel line length can cause problems with the transfer between the primary and secondary fuel. The solenoid operated shutoff valves should be energized to run and be mounted as close to the regulators as possible. During normal operation using the primary fuel, both solenoid valves should be engaged. The primary fuel supplied by the low BTU regulator has greater pressure than the secondary fuel pressure. Any time the primary fuel is present, the propane gas regulator will stop the propane supply even though the solenoid valve is energized.When the primary fuel supply pressure runs low, the deactivation of the pressure switch will change the engine timing to the secondary fuel supply. There must be a customer supplied system to de-energize the primary solenoid valve in order for the switch to take place. As fuel is used between the natural gas regulator (15) and the carburetor, the pressure in the supply line will drop. The propane gas regulator