Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionAir Suction Valve Installation
Install the air suction valve so that opening [A] of the reed
faces downward.
Apply a non-permanent locking agent to the threads of
the air suction valve cover bolts [A], and tighten them.
Torque - Air Suction Valve Cover Bolts: 9.8 N·m (1.0 kgf·m,
87 in·lb)
...
Vehicle-down Sensor Input Voltage Inspection
NOTE
Be sure the battery is fully charged.
Turn the ignition switch to OFF.
Disconnect the vehicle-down sensor connector and connect
the measuring adapter [A] between these connectors
as shown in the figure.
Main Harness [B]
Vehicle-down Sensor [C]
Special Tool - Measuring Adapte ...
Check 2-2: Fuel Level Warning Inspection
Remove:
Fuel Tank (see Fuel Tank Removal in the Fuel System
(DFI) chapter)
Connect the resistor(s) [A] (about 50 to 100 Ω) between
the fuel pump connector terminal [B] of the main harness
side and the battery negative (–) terminal [C] as shown.
Turn the ignition switch ...