DIODE AS 9N1202 - Caterpillar

High Pressure Gas Carburetor
Illustration 1 g00676469
High-pressure gas carburetor
(1) Idle adjustment screw
(2) Load adjusting valve
(3) Throttle stop screw
(4) Throttle lever
(5) Throttle shaft slot
Turn idle adjustment screw (1) counterclockwise for four rotations from the closed position.
For initial setting of the Impco 200 carburetor, turn load adjusting valve (2) to the center between the "L" and the "R". The "L" represents a lean fuel mixture. The "R" represents a rich fuel mixture.Low Idle Adjustment
Disconnect the governor linkage at throttle lever (4).
Turn screw (3) until the throttle closes. Then turn the screw in order to slightly open the throttle. Contact of the throttle plate with the throttle stop will cause premature wear on the throttle plate and the throttle body. Keep the throttle plate slightly open for the minimum fuel position.
Move the control lever for the governor to the minimum fuel position.
Adjust the length of the linkage between the governor and lever (4). Make sure that the throttle plate and the governor are in the minimum fuel position.
Reconnect the linkage between the governor and lever (4).
Start the engine and adjust throttle stop screw (3) for the low idle. For more information on adjustment of the governor-to-carburetor linkage, refer to Specifications, "Governor Linkage".Low Pressure Gas Carburetor
Illustration 2 g00676615
Low-pressure gas carburetor
(1) Throttle
(2) Load adjusting valve
Turn load adjusting valve (2) clockwise until the screw is fully closed. Be careful not to overtighten the load adjusting valve.
Turn load adjusting valve (2) counterclockwise for 3.5 to 4 revolutions.
Start the engine and check the exhaust oxygen. Load Adjusting Valve
Table 1
Tools Needed Quantity
391-8170 EMISSIONS ANALYZER TOOL GP - (Bluetooth Module) (1) 1
393-0673 EMISSIONS ANALYZER TOOL GP (1) 1
1U-5470 Engine Pressure Group 1
(1) Either analyzer may be used.The load adjusting valve affects the air/fuel ratio. The valve determines whether the mixture is rich or lean. The following factors are influenced by the air/fuel ratio:
Fuel consumption
Engine power output
Engine stability
Engine component life
Deterioration of lube oilGenerally, the air/fuel ratio which produces the lowest fuel consumption produces more nitrogen oxides (NOx). This level of NOx can cause rapid deterioration of the lube oil through nitration.Richer air/fuel ratios reduce NOx levels. A rich air/fuel ratio will have the following effects on the engine:
Increase in fuel consumption
Increase in levels of carbon monoxide
Increased exhaust temperature
Reduced service life of valves
Higher costs for treatment of exhaust emissions and for maintenanceA lean air/fuel mixture will have the following effects on the engine.
Reduction in fuel consumption
Reduced exhaust temperature
Increase in levels of NOx
Reduction in power output
Increase in the tendency for misfiring of the engineThe most accurate method of adjusting the air/fuel ratio involves the use of an emissions analyzer. This method consumes the least amount of time as well. The measurement of free oxygen O2 in the exhaust gas is an indicator of air/fuel ratio. If optimum fuel consumption is of prime importance, an O2 level of one to two percent will be required. This setting requires close monitoring of oil performance. Oil change intervals may be reduced. For more information, see Application and Installation, LEKQ7254, "Lubrication Systems" and Operation and