Monster 659 Owner's Manual page 91

Connect the fuel sensor (11) to the main wiring harness.
E Position the lambda sensor cable (G) in the specific tab (H) on
the tank flange cover and secure it with a clamp.
Important
With the fuel tank lowered, the fuel level sensor
connector (11) should rest on the vertical cylinder head, as
shown in the figure.
90
11
G
fig. 89
H
fig. 90