Purging The Fuel System; Fuel System; Priming; Fuel Tank Cleaning And Flushing - Mercury TDI 4.2L Manual

6. Replace the O‑ring.
7. Insert the new fuel filter into the cannister. The filter will snap into place.
8. Lubricate the new O‑ring around the cannister with clean diesel fuel.
NOTE: Do not fill the canister with fuel.
9. Install the cannister onto the upper portion of the fuel filter assembly and hand‑tighten it.
10. Connect the water‑in‑fuel sensor to the wiring harness.
11. Connect the battery cables to the battery, connecting the negative (–) cable last.
12. Ensure the fuel tank is filled with fuel.
13. Turn the ignition switch to the "ON" position. The fuel pump will run for five seconds. Turn the ignition switch to the "OFF"
position and wait five seconds. Repeat this step six times.
14. Start the engine and let it idle for approximately 20‑30 seconds then shut the engine off.
15. Wait a few seconds and repeat step 13 two more times.
16. Check fuel filter and connections for leaks.
IMPORTANT: If leaks exist, check the connections and verify that all connections and the cannister are properly seated. If
leaks continue, stop the engine immediately and contact your Mercury Diesel–authorized repair facility.

Purging the Fuel System

The fuel injection pump generates pressure in excess of 13790 kPa (2000 psi), which is high enough to penetrate or cut the
skin. Do not use your fingers to feel for fuel leaks and wear personal protective equipment when servicing the fuel system.
NOTE: It is possible that the engine will not start if the fuel system has not been completely purged of air.
1. Ensure that the fuel tank is filled with fuel.
2. Turn the ignition switch to the "ON" position. The fuel pump will run for five seconds. Turn the ignition switch to the "OFF"
position and wait five seconds. Repeat this step six times.
3. Start the engine and let it idle for approximately 20–30 seconds, then shut the engine off.
4. Wait a few seconds and repeat step 3 two more times.

Fuel System

Priming

NOTE: Follow this procedure if the fuel system was run dry or if part of the fuel system was drained for a service function.
1. Turn the ignition switch to the "ON" position and the fuel pump will run for five seconds. Turn the ignition switch to the
"OFF" position and wait five seconds. Repeat this step six times.
2. Start the engine.

Fuel Tank Cleaning and Flushing

IMPORTANT: Diesel fuel should not be left in the tank during winter storage, as an accumulation of rust, sludge and wax
residue will form.
Refer to the boat manufacturer's instructions and clean the fuel tank at specified intervals. Unless specified otherwise, flush and
clean the diesel fuel tank every 1000 hours or five years, whichever occurs first.

Seawater System

Seawater Pump Impeller Inspection

The seawater pump impeller must be inspected (and replaced, if necessary) at the interval specified by the maintenance
schedule. It is recommended this task be performed at a Mercury Diesel–authorized repair facility.
1. Close the seacock.
90-8M0114081 DECEMBER 2015
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WARNING
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Section 4 - Maintenance
Page 49