852551T Force CARBURETOR (FO-3C)

Introduction
This Special Instruction includes the installation procedures and the start up procedures for G3300 and G3400 engines. The correct start up adjustment of the engine is essential for the following reasons:
long engine life
good fuel economy
acceptable emissionsService technicians should have a thorough understanding of the relationship between the fuel system and the ignition system. The technician must also be familiar with the Service Manual, "Systems Operation Testing And Adjusting" Section and the Service Manual, "Operation And Maintenance" Section.References
G3300 Gas Engine Performance, LEBQ4197
G3400 Industrial Engine Performance, LEBQ6483
G3400 Generator Set Engine Performance Data Books, LEBQ6484
G3300 Service Manual
G3400 Service Manual
Methane Number Program, LEKQ6378
EIS Diagnostic Code Card, RENR1234
Table 1
Tools Needed    
Part Number    Description    
7X-1400     Electronic Tool Group (1)    
NEXG4511     Electronic Tool Group (1)    
140-2304     Electronic Control Programmer (2)    
8T-0452     Manometer Gauge    
156-1060     Emissions Analyzer Group    
8T-5160     Setting Tool Group    
( 1 ) For 3400 EIS engines only. Refer to Using The NEXG4511 Spark Ignited Engine Service Program Module, SEHS8806 for more information on using the Digital Diagnostic Tool. Also refer to Service Program Module For Spark Ignited Engines, NEXG4511. You must have the chip in order for the 7X-1400 Electronic Tool Group to work.
( 2 ) For Engines equipped with ProAct Speed Control.Required Information
Ignition Timing
A complete fuel analysis must be conducted prior to putting the engine into service. Obtain a fuel analysis in order to determine the BTU content and calculate the Methane Number. The BTU content indicates the amount of energy that is available in the fuel. The Methane Number indicates the ability of the fuel to be ignited. The Methane Number is determined when you input the constituents of the fuel into the Methane Number Program, LEKQ6378. Use the Methane Number and the Engine Performance Book, "Fuel Usage Guide" in order to determine the ignition timing.Obtain several samples of fuel if the quality is expected to change. If the chemistry of the fuel will vary during engine operation, use the lowest expected value in order to determine ignition timing.Maximum Load
Refer to the Engine Performance Book in order to determine the engine power derates for altitude, temperature and Methane Number. Use the derate range in order to determine the maximum engine load.Inlet Manifold Pressure At Full Load
For generator set applications, use the generator power output to determine the engine load. For other applications, use the inlet manifold pressure to estimate the engine load. The Engine Performance Book provides inlet manifold pressures for a specific timing and emissions setting. If the engine power is derated, interpolate the desired inlet manifold pressure between the 100 percent and the 75 percent load ratings.Note: The inlet manifold pressure may be used if the engine timing and the exhaust oxygen are set properly.Exhaust Oxygen Level
The 156-1060 Emissions Analyzer or equivalent is required in order to properly set up a gas engine. The engine should be set up at the desired full load with the data that was taken at 100 percent load. Do not exceed the maximum load.Carburetor Adjustments
The carburetor and the gas pressure regulator require adjustment when the engine is installed. The initial factory settings are based on the following conditions:
an ambient temperature of 25 °C (77 °F)
a barometric pressure of 96 kPa (28.4 in Hg)
the use of a natural gas pipeline with a Low Heating Value of 33.74 kJ/L (905 BTU/cu ft)The factory ratings comply with SAE J1349 Standards. An engine that does not use natural gas may be shipped with optional orifices and valves. An engine of this type will be run with a catalyst and an air/fuel ratio control. Engine applications that do not use dry pipeline gas may be shipped with carburetor jets and valves for field installation. Contact your Caterpillar dealer for more information.Gas Pressure Regulator
The gas pressure regulator requires adjustment when the engine is installed. Use only Caterpillar approved regulators in order to avoid problems with performance. A balance line for the regulator is required in all gas engines. This line compensates for changes in boost pressure or air filter restriction. Refer to the Systems Operation Manual for details.Note: The supply line to the gas pressure regulator must be of adequate diameter in order to provide constant pressure to the regulator from idle to full load. Do not use supply lines that are smaller than the inlet to the pressure regulator.Governors
It may be necessary to make one or more of the following governor adjustments during start-up:
low idle speed
high idle speed
droop
gainRefer to the Service Manual for further information.Hydramechanical
The Hydramechanical Governor is a simple governor for the G3300 and some of the G3400 applications that do not require close speed regulation. The standard Hydramechanical Governor has approximately 7 percent droop at 1800 rpm. Special springs can be ordered in order to lessen the droop.Pressure Compensated Simple Governor (PSG)
The PSG Governor is a mechanical-hydraulic governor that is capable of isochronous speed control. The speed is controlled by a simple hand lever. A pneumatic control is available for remote speed control. A motor (24 VDC) is also available for remote speed control. Refer to Service Manual, SENR6514, "PSG Governor".Flo-Tech
The Flo-Tech system is