A fuel pump module is liquid-tightly mounted in an opening of a vehicle
fuel tank. The fuel pump module includes a residual fuel detector provided
near the fuel tank. The residual fuel detector includes a diaphragm having
a first diaphragm for receiving fuel pressure Pg by a head and atmospheric
pressure Po, and a diaphragm portion for receiving atmospheric pressure Po
and internal pressure Pi. The residual fuel detector detects the amount of
fuel remaining in the fuel tank on the basis of these kinds of pressure
Po, Pg and Pi. At the same time, the residual fuel detector detects the
in-tank pressure Pt of the fuel tank on the basis of Po and Pi.
