SECTION 2.05 FUEL SYSTEM DESCRIPTION FUEL SYSTEM COMPONENTS

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1 SECTION 2.05 FUEL SYSTEM DESCRIPTION FUEL SYSTEM COMPONENTS The engine fuel system consists of the following engine mounted components: Carburetors Throttle valves Fuel pressure regulator and balance line(s) Fuel shutoff valve The carburetor uses an air valve to meter the fuel gas proportionally to the air flow. A regulator controls the fuel gas supply pressure to the carburetor. The IMPCO carburetors consist of a main body with a venturi and a diaphragm operated gas metering valve (see Figure , Figure , Figure and Figure ). The amount of air passing into the engine is measured by an air-flow measuring valve which rises proportionally to the air volume passing through the carburetor. The gas metering valve is attached to the air measuring valve which opens the gas valve proportionally to the air volume. This controls the air/fuel ratio throughout the engine speed and load range. Figure H24G IMPCO 600 Carburetor POWER ADJUSTMENT SCREW Figure F18/H24GSID IMPCO 600 Carburetor Figure F18/H24GL IMPCO 400 Carburetor FORM 6284 Third Edition

2 Figure F18/H24GLD IMPCO 600D Carburetor Deltec carburetors have low inlet restriction for improved performance. The carburetor's flat tracking provides desirable performance and low emissions and allows lean operation with low octane fuels (see Figure ). WARNING The Deltec carburetion system must have a positive gas shutoff valve that opens upon cranking and closes whenever engine rotation stops. Failure to provide the valve will cause an explosive environment resulting in severe personal injury or death. Deltec carburetors contain no moving parts. The main adjustment screw (MAS) controls the fuel gas to the carburetor (see Figure and Figure ). The carburetor consists of a main body with a perforated venturi insert that allows fuel gas to be drawn into the air stream. The size and number of the holes controls the air/fuel mixture. Figure F18/H24GLD Deltec Carburetor GL The IMPCO carburetor used on the GL engine uses an air valve to meter the fuel gas proportionally to the air flow (see Figure ). A regulator controls the fuel gas supply pressure to the carburetor. A carburetor inlet pressure range of ± 12 mm (6 ± 0.5 in.) water column is typical for the L36/P48GL operating on 900 Btu LHV natural gas. S DELTEC MAIN ADJUSTING SCREW Figure IMPCO GL Carburetors The carburetors consist of a main body with a venturi and a diaphragm-operated gas metering valve. The amount of air passing into the engine is measured by two air-flow measuring valves which rise proportionally to the air volume passing through the carburetor. The gas metering valves are attached to the air measuring valves which open the gas valves proportionally to the air volume. This controls the air/fuel ratio throughout the engine speed and load range. Figure F18/H24GLD Deltec Carburetor FORM 6284 Third Edition

3 FUEL PRESSURE REGULATOR GL The GL engines typically use a Y692 cast iron regulator which reduces the supply line pressure (25-50 psi) to a carburetor inlet pressure above turbocharger boost pressure (see Figure ). From this regulator, the fuel gas is directed to the carburetor. BALANCE LINE BALANCE TUBE SPRING OUTLET VALVE DISC Figure L36/P48GL Fuel Regulator GLD/GSID PUSHER POST ORIFICE INLET Figure Fuel Pressure Regulator Some GLD/GSID engines use Deltec carburetors (see Figure ). The Deltec carburetor has low inlet restriction for improved performance. A gas over air pressure range of 0 ± 12 mm (0 ± 0.5 in.) water column is typical for the L36/P48GLD/GSID operating on 900 Btu LHV natural gas. BALANCE LINE A balance line is required to connect the pressurized air in the intercooler to the spring side of the fuel regulator diaphragm (see Figure and Figure ). This balance line will cause the regulator to change the carburetor gas pressure as the intake air pressure changes. BALANCE LINE Figure GLD/GSID Deltec Carburetor Figure H24G IMPCO 600 Carburetor Balance Line WARNING The Deltec carburetion system must have a positive gas shutoff valve that opens upon cranking and closes whenever engine rotation stops. Failure to provide the valve will cause an explosive environment resulting in severe personal injury or death. Deltec carburetors contain no moving parts. The main adjustment screw (MAS) controls the fuel gas to the carburetor (see Figure ). The carburetor consists of a main body with a perforated venturi insert that allows fuel gas to be drawn into the air stream. The size and number of the holes controls the air/fuel mixture. FORM 6284 Third Edition

4 THROTTLE VALVES MAIN ADJUSTMENT SCREW Figure GLD/GSID Deltec Fuel Adjustment FUEL PRESSURE REGULATOR ZERO PRESSURE (IF EQUIPPED) On Deltec fuel systems the fuel regulator is often called a zero pressure regulator (ZPR). This term is used to refer to the fuel pressure at the regulator outlet /carburetor inlet ( mm (-1 to 2 in.) H 2 O), which is very close to the value of the air pressure going into the carburetor. The basic principle is that the Deltec will draw in the amount of fuel it needs (through the venturi), but that fuel should not be under pressure nor should it be under a vacuum (in reference to the air). THROTTLE VALVES The flow of air into the engine is controlled by the governor operated throttle valves located downstream from the carburetor (see Figure and Figure ). Figure L36/P48GL Throttle Valves MANUAL FUEL SHUTOFF VALVE (IF EQUIPPED) All VGF engines CAUTION include hand throttle controls for emergency shutdown procedures. Make sure that the hand throttle is maintained in the open position during startup and normal running conditions. Disregarding this information could result in product damage and/or personal injury. The fuel solenoid shutoff valve is located at the gas fuel inlet to the regulator valve (see Figure ). This valve is electrically actuated by a safety switch powered by the magneto. An electrical signal causes the gas valve to close off the fuel supply for normal and emergency shutdowns. The latching valve should be turned 1/4 turn clockwise to latch the valve open for starting. The manual lever can be rotated clockwise to manually close the valve for shutdown. THROTTLE VALVE TRIP ARM COIL VALVE SEAT Figure F18/H24 Throttle Valve OUTLET LATCH VALVE INLET VENT PLUG Figure Shutoff Valve FORM 6284 Third Edition

5 LEFT BANK AFFECTS RIGHT BANK CYLINDERS LEFT BANK INTAKE MANIFOLD FRONT FLOW FROM LB FLOW FROM RB RIGHT BANK AFFECTS LEFT BANK CYLINDERS RIGHT BANK INTAKE MANIFOLD Figure L36/P48 GLD/GSID Air/Fuel Flow As Viewed From The Top At rated speed, the L36/P48GLD/GSID carburetors feed the opposite cylinder bank. Any leaks in one bank of air filters, air ducting systems or carburetor will affect the opposite bank cylinders (see Figure ). OPERATION Rotate the manual lever counterclockwise to open the latch valve for starting, this causes the plunger to lift away from the valve seat and latches the trip arm. When the safety switch actuates, a circuit is completed through the coil, causing a magnetic action that releases the trip arm. Spring tension forces the plunger down on the valve seat, sealing off fuel gas flow. Gas pressure on top of the plunger helps to assure a positive seal. Once the valve has operated, it must be manually reset before restarting the engine. CUSTOM ENGINE CONTROL AIR/FUEL MODULE SYSTEM SYSTEM DESCRIPTION This section gives a brief introduction to Waukesha's Custom Engine Control (CEC) Air/Fuel Module (AFM) system. For complete information on the system, see Form 6263 (Software Version 2.8a) or Form 6286 (Software Version 4 Series), AFM Custom Engine Control Air/Fuel Module, Installation, Operation And Maintenance. The CEC AFM system is designed to control the air/fuel ratio of Waukesha's gaseous fueled VGF engines including stoichiometric and lean burn, naturally aspirated and turbocharged. Basic information about the engine model and application is programmed to the AFM using a personal computer (PC). An engine's air/fuel ratio defines the amount of air in either weight or mass in relation to a single amount of fuel supplied for combustion. Air/fuel ratio influences engine power, emissions, and fuel economy. By controlling an engine's air/fuel ratio with the AFM system, you will benefit in fuel savings, emissions control, and/or peak engine performance. The AFM system regulates and maintains the engine's air/fuel ratio even with changes in engine load, speed, fuel pressure, and fuel quality. FORM 6284 Third Edition

6 The AFM system is programmed at the engine site with a PC and is customized for the engine based on site specific information to run in one of four control modes: catalyst, best power, best economy, or lean burn. Catalyst and best power/economy modes apply to stoichiometric or rich burn engines. Lean burn mode only applies to lean burn engines. OPERATOR INTERFACE The AFM module is equipped with several features to inform site personnel of system status. These features include: Power and Alarm lights (LED display) on the front panel of the AFM module (see Figure ) The green Power LED is lit any time power is applied to the AFM module The yellow Alarm LED is lit any time the AFM system's diagnostic functions are activated or when AFM execution has been stopped by the operator (such as during the saving of a dataset) an alpha-numeric liquid crystal display (LCD display) visible from the front of the AFM module allows the operator to monitor important system parameters a sealed membrane keypad located on the front of the AFM module LCD DISPLAY LED DISPLAY THEORY OF OPERATION The AFM system controls engine air/fuel ratio and consists of three basic components: an oxygen sensor, stepper motor, and AFM module. The AFM system is a closed-loop process that looks at system outputs and adjusts system inputs according to preprogrammed instructions. The AFM system functions by monitoring oxygen levels in the exhaust gases with an oxygen sensor located in the engine s exhaust stream (see Figure ). The oxygen level, detected by the sensor, is then fed to the AFM module through an electrical signal. If the oxygen level detected by the sensor is different than the programmed oxygen setpoint, the AFM module directs the actuator to adjust the gas over air pressure of the fuel regulator. The actuator adjusts the fuel regulator setting, within programmed limits, by increasing or decreasing the spring pressure acting on the regulator diaphragm. The design gives very accurate positioning capability. This assembly essentially automates the manual adjusters that are sold with many Waukesha engines. The regulator adjustment riches or leans the air/fuel ratio. A thermocouple is used to assure that temperatures are high enough for correct operation of the sensor. A programmed minimum temperature must be achieved before closed-loop control is enabled. A programmed maximum temperature is also incorporated as a safety to shut down operation on high exhaust temperature conditions. The oxygen sensor provides continuous feedback of oxygen levels to the AFM module. The AFM module makes the necessary actuator adjustments to correctly control the engine's air/fuel ratio. KEYPAD Figure CEC Air/Fuel Module FORM 6284 Third Edition

7 OXYGEN SENSOR ELECTRICAL SIGNAL AFM MODULE REGULATOR WITH ACTUATOR Figure AFM System s Closed-Loop Process FORM 6284 Third Edition