Mercury Racing 500R - Engine Start & Control

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. An 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.
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.
OPERATION
eng 75 