8866A37 Mercruiser GEAR HOUSING ASSEMBLY (1.36:1 - 1.50:1 Ratio)

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Schematic for the fuel level sensorTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF position.
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J1/P1 ECM connectors (left side engine view)
Thoroughly inspect the J1/P1 ECM connectors. Refer to Troubleshooting, "Electrical Connectors-Inspect" for details.
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P1 terminals that are associated with the fuel level sensor (P1-5) Fuel level sensor signal (P1-68) Sensor return
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P803 Fuel level sensor connector (P803-1) Fuel level (P803-2) Sensor return
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the fuel level sensor.
Check the allen head screw on the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points from the fuel level sensor to the ECM.Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The connectors and the wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem in the connectors and/or the wiring.Repair: Repair the circuit. Verify that the repair eliminates the problem.STOPTest Step 2. Confirm the Fuel Level in the Tank
Visually check the fuel level in the tank.
Compare the fuel level in the tank to the indicator on the fuel level sender.Expected Result:The fuel level in the tank agrees with the indicator on the fuel level sender.Results:
OK - Proceed to Test Step 3.
Not OK - The indicator on the fuel level sender does not reflect the actual fuel level in the tank.Repair: Replace the fuel level sender. Verify that the repair eliminates the problem.STOPTest Step 3. Check the Status of the Fuel Level
Turn the keyswitch to the OFF position.
Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the keyswitch to the ON position.
Observe the status of "Fuel Gauge" on Cat ET.Note: The "Fuel Gauge" on Cat ET represents the percentage of fuel level in the tank.
Turn the keyswitch to the OFF position.Expected Result:The status of "Fuel Gauge" displays the correct fuel level.Results:
OK - Cat ET displays the correct fuel level.Repair: The fuel level sensor appears to be operating correctly at this time. There may be an intermittent problem in the harness or in a connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.STOP
Not OK - Cat ET does not display the correct fuel level. Proceed to Test Step 4.Test Step 4. Check the Resistance of the Fuel Level Sender
Disconnect the fuel level sender from the fuel level buffer.
Measure the resistance between the terminals on the receptacle for the fuel level sender.The correct resistance is between 0 and 3.5 Ohms when the indicator is on "F". The correct resistanceis between 92 and 98 Ohms when the indicator is on "E".
Reconnect the fuel level sender.Expected Result:The resistance is less than 98 Ohms.Results:
OK - The resistance is less than 98 Ohms. The fuel level sender appears to be OK. Proceed to Test Step 5.
Not OK - The resistance is out of the range.Repair: Replace the fuel level sender. Verify that the repair eliminates the problem.STOPTest Step 5. Check the Supply Voltage to the Buffer
Disconnect the connector at the fuel level buffer.
Turn the keyswitch to the ON position.
Measure the voltage across terminal A (+Battery) and terminal B (digital return) at the breakout.Expected Result:The supply voltage is approximately 24 VDC.Results:
OK - Battery voltage is present at the connector for the fuel level buffer. The buffer is receiving the correct supply voltage. Proceed to Test Step 6.
Not OK - The buffer is not receiving the correct supply voltage.Repair: Check the machine's circuit breaker panel for a tripped circuit breaker. Verify that the ground circuit has continuity. Repair any problems that are found with the circuit. Verify that the repair eliminates the problem.STOPTest Step 6. Check the Isolated Signal Frequency and the Duty Cycle
Install a 7X-6370 Adapter Cable As (3-PIN BREAKOUT) at the connector for the fuel level buffer.
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(A) +24 V Supply (B) Digital Return (C) Signal
Remove the signal wire from the harness side of the connector for the fuel level buffer. Leave the breakout in place.
Turn the keyswitch to the ON position.
Measure the frequency and the duty cycle between terminal B (digital return) and terminal C (signal) at the breakout.
Turn the keyswitch to the OFF position.
Reinstall the signal wire in the connector and remove the breakout. Leave the connector disconnected.Expected Result:The frequency is between 5 and 6.5 kHz. The duty cycle is between 20 and 95 percent.Results:
OK - The frequency and the duty cycle are correct. The buffer is producing a valid signal. Proceed to Test Step 7.
Not OK - The frequency and the duty cycle are not correct.Repair: The buffer is not producing a valid signal. Replace the fuel level buffer. Verify that the repair eliminates the problem.STOPTest Step 7. Check the Harness for a Short Circuit
Ensure that the keyswitch is in the OFF position and that