Engine System - LPG 179Service Manual – CS7000
Achieves one but not ALL RPM modes.
The approach to diagnosing an engine RPM control problem is to check the inputs to the L series actuator. If
the inputs are good and the output is bad, the conclusion is that the actuator is the problem. However, don’t
forget that insufcient fuel supply or a restricted exhaust could appear like an RPM control problem if the
engine cannot run well enough to achieve a higher RPM.
Possible Causes:
• Failed Engine Speed Sensor
• Actuator linkage
• Actuator power supply
• Actuator
• Wiring
• Main Machine Controller
Diagnostic steps
1. Visually inspect the linkage between the actuator arm and the carburetor throttle lever.
– Is the linkage okay?
◦ If not, repair
◦ If so, go to next step.
2. Check the power and ground supplies to the actuator.
– Is there sufcient power and ground?
◦ If so, go on to check the Engine RPM Sensor input.
◦ If not, repair.
3. Check the Engine RPM Sensor input. (Check the AC voltage while the engine is running or check
resistance of sensor through wiring harness from the actuator connector.)
– Is the Engine RPM sensor input okay?
◦ If so, go on to check the speed request inputs.
◦ If not, repair.
4. Check the speed request inputs - With the engine running press the engine speed button and check for
12v to the throttle 1 wire at the actuator.
– Is 12v present on the throttle 1 wire?
◦ If so, replace the actuator
◦ If not, check the wiring between the main machine controller and the governor controller.
◦ If the wiring is okay, check the output coming out of the main machine controller.
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