Fuel System; Fuel System Precautions; Fuel Line Inspection; Vst Vent And Cooling Hose Inspection - Mercury 15 EFI FourStroke Service Manual

Maintenance
Flush the internal water passages of the outboard with fresh water after each use in salt, polluted, or muddy water. This will
help prevent a buildup of deposits from clogging the internal water passages.
IMPORTANT: The engine must be run during flushing in order to open the thermostat and circulate water through the water
passages.
1. Remove the propeller. Refer to Propeller Replacement.
2. Remove the plug from the flush fitting, and attach a water hose. Turn on the water to half of the maximum flow.
3. Start the engine and run it at idle speed in neutral shift position.
IMPORTANT: Do not run the engine above idle while flushing.
4. Check for a steady stream of water flowing out of the water pump indicator hole. Continue flushing the outboard for 3–5
minutes, carefully monitoring the water supply at all times.
5. Stop the engine, turn off the water, and remove the water hose.
6. Install the plug into the flush fitting.
7. Install the propeller.

Fuel System

Fuel System Precautions

Fuel is flammable and explosive. Ensure that the key switch is off and the lanyard is positioned so that the engine cannot
start. Do not smoke or allow sources of spark or open flame in the area while servicing. Keep the work area well ventilated
and avoid prolonged exposure to vapors. Always check for leaks before attempting to start the engine, and wipe up any
spilled fuel immediately.
Before servicing any part of the fuel system, stop the engine and disconnect the battery. Drain the fuel system completely. Use
an approved container to collect and store fuel. Wipe up any spillage immediately. Material used to contain spillage must be
disposed of in an approved receptacle. Any fuel system service must be performed in a well ventilated area. Inspect any
completed service work for sign of fuel leakage.

Fuel Line Inspection

Visually inspect the fuel line and primer bulb for cracks, swelling, leaks, hardness, or other signs of deterioration or damage. If
any of these conditions are found, the fuel line or primer bulb must be replaced.

VST Vent and Cooling Hose Inspection

Visually inspect the fuel vapor vent hoses (between the vapor separator tank and the vent tank) and the vapor separator tank
(VST) cooling hoses for cracks, swelling, leaks, hardness, or other signs of deterioration or damage. If any of these conditions
are found, the hoses must be replaced.

Draining Water from the Fuel Filter

Check the fuel filter for water accumulation or sediment. If water is in the fuel, drain the water. If the filter appears to be
contaminated, remove and replace.
1. Read Fuel System Precautions, preceding.
2. Inspect the water‑separating fuel filter. If water is present, the red ring inside the filter assembly should float at the water
level.
Page 1B-4
Flush fitting
WARNING
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© 2018 Mercury Marine
62842
90-8M0125265 eng NOVEMBER 2017