812843A 1 Mercury VALVE ASSEMBLY

Probable Causes
Diagnostic codes
Electrical connectors
ECM connection
Fuel supply
Intake manifold pressure
Throttle position sensorRecommended Repairs
Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.
Diagnostic Codes
Check for active diagnostic codes on the electronic service tool. Troubleshoot any active codes before continuing with this procedure.Electrical Connectors
Refer to Troubleshooting, "Electrical Connectors - Inspect".
Repair the electrical connectors or replace the electrical connectors.
Ensure that all the connector seals are in place and that the connectors have been correctly installed.
Ensure that the repairs have eliminated the fault. If the fault has not been eliminated proceed to "ECM Connection". ECM Connection
Check that the J1/P1 connector is correctly connected.
Verify the proper pin positions for the power connections and the ground connections for the Electronic Control Module (ECM).
If a fault is suspected with the ECM power and ground connections refer to Troubleshooting, "Electrical Power Supply Circuit - Test".
Verify that the ECM connections for the power and ground connections at the fuel pump are connected properly.
If a fault is suspected with the fuel injection pump power and ground connections refer to Troubleshooting, "Fuel Injection Pump Circuit - Test".
Repair any faults and ensure that the faults have been eliminated.
If the repairs do not eliminate the faults, proceed to "Fuel Supply". Fuel Supply
Check the fuel pressure. Refer to Systems Operation, Testing and Adjusting, "Fuel System Pressure - Test".
Ensure that the fuel system has been primed. Refer to Systems Operation, Testing and Adjusting, "Fuel System - Prime".
Check the diesel fuel for contamination. Refer to Systems Operation, Testing and Adjusting, "Fuel Quality - Test".
Check for air in the fuel system. Refer to Systems Operation, Testing and Adjusting, "Air in Fuel - Test".
Check that the fuel lines are tight and secured properly.
Check for fuel supply lines that are restricted.
Check the fuel filters.
Visually check the fuel tank for fuel. The fuel gauge may be faulty.
If the engine has a water separator, check for water in the fuel.
Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
If the temperature is below 0 °C (32 °F), check for solidified fuel (wax).
If the repairs do not eliminate the faults, proceed to "Intake Manifold Pressure". Intake Manifold Pressure
Use the electronic service tool to verify the intake manifold pressure.
Turn the keyswitch to the ON position.
Check the intake manifold pressure. The pressure should read 0 kPa (0 Psi).
Use the electronic service tool to check for the following logged diagnostic codes:
102-03 Boost Pressure Sensor voltage above normal
102-04 Boost Pressure Sensor voltage below normalIf either of these diagnostic codes are logged, proceed to Troubleshooting, "Engine Pressure Sensor Open or Short Circuit - Test".
If no faults are found proceed to "Throttle Position Sensor". Throttle Position Sensor
Use the electronic service tool to observe the throttle position status.
Operate the engine at a maximum no-load speed. Check that the throttle position (%) is inside calibration (80 to 87%) at high idle if the programmed limit for the upper demand cannot be obtained.
If the engine speed is erratic, reduce the engine speed.
Check that the calibration of the low idle is within 20 to 27%.
Slowly increase the engine speed. Check that the engine speed is steady. Check that the position increases with more throttle.
If the fault is still apparent, refer to Troubleshooting, "Throttle Position Circuit - Test".