5034031 JOHNSON MODULE, Engine control - 60HP

"Low Power/Poor or No Response to Throttle". If the symptom can be repeated, continue with this procedure.The probable root causes are listed below:
Cold Mode Operation
Throttle input signal
Electrical connector
Fuel Injector
Fuel supply
Air inlet restrictions
Exhaust restrictions
Air shutoff
Valve adjustmentNote the conditions that caused the problem. Troubleshooting the symptoms under other conditions can give misleading results.Perform the following checks:
Use the Caterpillar Electronic Technician (ET) in order to verify that the engine has exited cold mode. During Cold Mode, injection timing is modified. The cylinders may cut out. Cold mode cylinder cutouts may cause variations in vibration and available power. This is normal operation.
Use Cat ET in order to monitor the temperature of the coolant. If the reading is incorrect, refer to the diagnostic functional test Troubleshooting, "Engine Sensor Open/Short Test".
Use Cat ET in order to monitor the status of the throttle. Observe the throttle position. The throttle position should be stable. The throttle position should reach 100 percent. Refer to the diagnostic functional test Troubleshooting, "Speed Control".
Check for correct installation of the connectors for the Electronic Control Module (ECM) J2/P2 and the connectors for the Electronic Fuel Injectors J4/P4 through J19/P19. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".
Use Cat ET to determine if any active diagnostic codes are present for the Injector Solenoids. Check that the injector trim codes have been entered. Use Cat ET to determine if any logged diagnostic codes are present for the Injector Solenoids. Perform the Injector Solenoid Test. Observe that the Injector Solenoids are being energized on the Cat ET. Perform the Cylinder Cutout Test. Locate the misfiring cylinder. Refer to the diagnostic functional test Troubleshooting, "Injector Solenoids".
Check fuel lines for the following problems: restrictions, collapse, pinched line and loose fittings. Repair the lines and/or replace the lines. Refer to the diagnostic procedure Testing and Adjusting, "Fuel System Inspection".
Check the fuel tank for foreign objects which may block the fuel supply. Check for air in the low pressure fuel supply system after you perform the following procedures:
Replacing the fuel filters
Working on the low pressure fuel supply circuit
Replacing fuel injectors
Purge air from the low pressure fuel supply circuit with the hand priming pump and by cranking the engine in 30 second cycles. After you crank the engine, stop for two minutes. This will allow the starting motor to cool. Loosen the vent plug at the fuel return. The plug is located on the rear upper left side of the engine block. Hand prime the engine again if air in fuel continues. A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel.
Check fuel quality. In temperatures below 0 °C (32 °F), check for solidified fuel (wax). Refer to Special Publication, SEBD0717, "Diesel Fuels And Your Engine". Check the fuel pressure with engine cranking. Check the fuel pressure at the filter. Refer to Testing and Adjusting, "Fuel Pressure". Refer to Testing and Adjusting, "Fuel Pressure". Refer to the Specifications, "Fuel Pressure Regulator" for correct pressure values. If pressure is low, check for plugged fuel filters. If the fuel pressure is still low, check the following items: fuel transfer pump, fuel transfer pump coupling and fuel pressure regulating valve. Check for a problem with the combustion system.
Check for restrictions in the air inlet system. Refer to Testing and Adjusting, "Restriction of Air Inlet and Exhaust".
Check for restrictions in the exhaust system. Refer to Testing and Adjusting, "Restriction of Air Inlet and Exhaust".
Check that both air shutoff valves are OPEN.
Refer to Testing and Adjusting, "Fuel Pressure".