Yamaha F75F - Measuring the Fuel Pressure

Fuel system
6-2
• After disconnecting the quick connector “1”,
be careful not to lose the retainer “2”.
• Cover the quick connector and vapor separa-
tor with a plastic bag to prevent damage and
dirt from entering them.
Measuring the fuel pressure
Cover the fuel components using a rag to pre-
vent fuel from spilling out.
1. Measure:
• Fuel pressure
Out of specification  Check the fuel line.
a. Reduce the fuel pressure. See “Re-
ducing the fuel pressure” (6-1).
b. Disconnect the quick connector from
the fuel
rail. See “Disconnecting the
quick connector” (6-1).
c. Connect the special service tool “1” to
the quick
connector and the fuel rail.
d. Connect the special service tool “1”.
To prevent fuel from leaking out, screw in
the gauge gently until it is connected firmly.
e. Install the flywheel magneto cover.
f. Turn the engine start switch to ON,
and then
measure the fuel pressure
within 5 seconds.
• The fuel pressure will decrease 5 seconds af-
ter the engine start switch is turned to ON.
• The high-pressure fuel pump does not oper-
ate when the engine start switch is turned to
ON again within 10 seconds
after turning the
engine start switch to OFF.
g. Start the engine and warm it up until
the engine idle speed stabilizes at
700–800 r/min.
h. Measure the fuel pressure.
i. Turn the engine start switch to OFF.
j. Reduce the fuel pressure. See “Re-
ducing the fuel pressure” (6-1).
k. Disconnect the special service tool.
Fuel pressure at engine start switch
to “ON” within 5 seconds
310 kPa (3.1 kgf/cm², 45.0 psi)
Fuel pressure at idle speed
320 kPa (3.2 kgf/cm², 46.4 psi)
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2
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Fuel pressure gauge adapter “1”
90890-06946
Fuel pressure gauge “1”
90890-06753
1