Engine Break-In Procedure; Fuel Supply Module Priming Procedure - Mercury 300R HD CMS Mechanical Operation And Maintenance Manual

Engine Break‑in Procedure
IMPORTANT: Failure to follow the engine break‑in procedures can result in
poor performance throughout the life of the engine and can cause engine
damage. Always follow break‑in procedures.
1. For the first two hours of operation, run the engine at varied throttle
settings up to 4500 RPM or at three‑quarter throttle, and at full throttle for
approximately one minute every ten minutes.
2. For the next eight hours of operation, avoid continuous operation at full
throttle for more than five minutes at a time.

Fuel Supply Module Priming Procedure

The fuel supply module (FSM) is not vented to the ambient air. The air trapped
in the FSM, fuel lines, and fuel rail, will be slightly compressed during the initial
ignition key on with a dry or drained fuel system. Additional key on events
under these conditions, will not compress the air further to finish the priming of
the FSM. Excessive number of key on events may eventually damage the fuel
pumps. The volume of air trapped in the FSM must be purged to prime the fuel
system. This can be achieved by connecting a tool to the fuel rail Schrader
valve fitting to quickly purge the system into an approved container, or by
cranking the engine.
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 when the fuel
system leading to the outboard is restrictive; antisiphon valve or holds a
relatively large volume of fuel because of a long fuel supply line or a vessel
mounted water‑separating fuel filter is installed. 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.
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OPERATION
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