803522A04 Mercury CARBURETOR

Sudden movement of the machine can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before troubleshooting.
1. Move the machine to a horizontal location. Move it away from all working machines and personnel. Put the transmission shift lever in the NEUTRAL position.2. Activate the parking brake.3. Stop the engine.4. Make sure the transmission rotary selector spool is in NEUTRAL (single neutral units) NEUTRAL-1 (double neutral units) position.5. Permit only two people in the cab (one operator and a service person). The machine operator must only operate the machine as told by the service person. The service person will look at all lights (LED's). Keep all other personnel either away from the machine or in view of the operator at all times. The Testing And Adjusting Procedures use the wiring, components and connectors as shown in the Engine Overspeed Indicator Schematic at the end of this module. For an accurate representation of the machine, see the respective machine Electrical System Schematic module.Codes And Abbreviations
Some connections between harnesses are made with metal connectors. These connectors have a ring that works like a nut to hold the connectors together. The metal connectors have ten or more contacts.In these types of connectors, each contact has a number or letter for identification. The description of the connections between harnesses is as follows. The number or letter inside the connector is the identification of the contact (pin or socket) in the connector. The number below the connector tells the total number of contacts in the connector. The letters above the connector are an indication of the harnesses as shown in a table on the schematic.Use the chart that follows for identification of wire colors. Troubleshooting
The Testing And Adjusting Procedures use the wiring, components and connectors as shown in the Engine Overspeed Indicator Schematic at the end of this module. For an accurate representation of the machine, see the respective machine Electrical System Schematic module.Loose harness connections may cause electrical problems, either permanent or intermittent (comes and goes). Make sure the connectors are fastened tight before other tests are made.Failure of an electrical component sometimes causes or is caused by the failure of one or more other components. Always find and correct the cause of electrical component failure before replacing the component.If a measurement for continuity is made with any Caterpillar Digital Multimeter and more than 1 or 2 ohms resistance is found, first find the cause of this resistance and correct it. Then continue to troubleshoot.
Voltage TesterThe Voltage Tester is used to check if voltage is present in a circuit. It cannot measure voltage. The light will come on when voltage is between 12 and 36 volts.
Circuit (Continuity) TesterThe Circuit Tester is used to check circuits without voltage for continuity. The light in the Circuit Tester is dim (not much light) with a 10 ohm resistance in the test circuit. The light is brighter (more light) with less resistance in the test circuit.
Caterpillar Digital MultimeterAny Caterpillar Digital Multimeter is used to measure voltage, current or resistance. It also is used to check diodes. The instructions that come with the multimeter tell how to use it for these different tests.
Test Wire AssembliesSome test procedures require a test wire assembly. The test wire assembly is used to connect machine ground to a connector pin or socket. The test wire assemblies are made up of an alligator (type of clamp) clamp, a piece of wire, electrical tape and a pin or socket. The above picture shows how these wire assemblies look. For good connections, solder one end of the wire to the pin or socket, and the other end of the wire to the alligator clamp. Then wrap with electrical tape.Problems
The Testing And Adjusting Procedures use the wiring, components and connectors as shown in the Engine Overspeed Indicator Schematic at the end of this module. For an accurate representation of the machine, see the respective machine Electrical System Schematic module.The engine overspeed control provides built-in diagnostic capabilities. These are designed to make service and maintenance of the system as simple as possible. When a problem has been detected, the engine overspeed control goes into the fault mode. While in the fault mode, the warning lamp will flash two times every two seconds (blink-blink-off, blink-blink-off). Also on OHT's, the warning horn is operating at the same time as the warning lamp (beep-beep-off, beep-beep-off).Two problems are detected by the engine overspeed control:* Problem 1 - The system is in the fault mode and diagnostic lamps #2, #3 and #4 are FLASHING once per second. If these conditions are present, the machine harness code is invalid.* Problem 2 - The system is in the fault mode and NO diagnostic lamps are ON. If these conditions are present, there is NO engine speed signal. The main purpose of red diagnostic lamp #4 is to indicate an internal failure of the engine overspeed control. Red diagnostic lamp #4 flashes when the engine overspeed control is failed. However, red diagnostic lamp #4 also flashes during: * The control self test - red diagnostic lamp #4 operates during the first six seconds after the key switch has been turned to RUN or START position. See Control Self Test.* A harness code failure - red diagnostic lamp #4 flashes along with diagnostic lamps #2 and #3. See Problem 1 - Harness Code.If red diagnostic lamp #4 flashes at anytime other than above, then the control is failed. Replace the engine overspeed control.Problem 1 - Harness Code
While in the fault mode, diagnostic lamps #2, #3 and #4 are FLASHING once per second. This indicates an unacceptable open or short to ground exists on the harness code wires. Procedure1. Turn the disconnect switch to the OFF position. Disconnect the harness connector plug from the engine overspeed control connector receptacle B. At the harness connector plug, check for continuity between machine GND and the four harness code connection points. See the Harness Code Continuity chart. * Continuity checks according