Mercury 200 Verado FourStroke Operation And Maintenance Manual page 69

PRIMING THE FSM WITH A PURGE TOOL
The use of a purge tool for priming the FSM is the preferred method, but is not
always practical. The objective is to purge the air entrained in the fuel system
through a purge tool connected to the fuel rail Schrader valve test port. During
the key "ON," opening the dump valve will allow the air to be purged from the
FSM and fuel rail. This method should be used on vessels where the fuel inlet
system to the outboard is restrictive; anti‑siphon valve or holds a relatively large
volume of fuel because of a long fuel supply line or water separating fuel filter.
If a primer bulb is installed, it can be used during the priming event to shorten
the amount of time required to start the engine.
1. Verify the engine is in a level vertical position.
2. Verify the vessel fuel supply line is connected to the outboard fuel system
inlet fitting.
3. Connect a fuel pressure gauge to the fuel rail Schrader valve.
4. Secure the fuel pressure gauge purge hose into an appropriate fuel
container to collect excess fuel.
5. Open the fuel pressure gauge purge valve and turn the ignition key "ON."
The fuel pumps will run for approximately five seconds.
6. Turn the ignition key "OFF" and then back "ON." The fuel pumps will run
for approximately five seconds. Continue this ignition key cycle until the
purged fuel is relatively clear of air bubbles.
NOTE: If the outboard fuel system does not prime within 15 key "ON" events,
check for leaks in the fuel supply line to the outboard. Repair as needed. If no
leak is found, the fuel supply system to the outboard may be too restrictive.
Correct the condition and try again.
7. Remove the fuel pressure gauge.
8. Turn the ignition key "ON." When the fuel pumps stop running, start the
engine. The engine may not start on the first attempt. The engine will run
rough at idle for up to two minutes while the residual air is purged from the
fuel system.
PRIMING THE FSM (RAN OUT OF FUEL CONDITION)
The use of a purge tool for priming the FSM is the preferred method, but is not
always practical. When the vessel fuel system is void of fuel volume, it can be
primed without the use of a purge tool. The objective is to purge the air
entrained in the fuel system through the fuel injectors during engine cranking to
allow fuel to enter the fuel module. This method can be used on vessels where
the fuel inlet system to the outboard is less restrictive and holds a relatively
small volume of fuel; a short fuel supply line, no water separating fuel filter, or
water separating fuel filter is already primed. If a primer bulb is installed, it can
be used during the priming event to shorten the amount of time required to start
the engine.
1. Verify the engine is in a level vertical position.
2. Verify the vessel fuel supply line is connected to the outboard fuel system
inlet fitting.
eng
OPERATION
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