Theory Of Operation; Oil Flow Diagram - Mercury 40 Service Manual

Theory of Operation

The major components of the oil injection system are
an oil tank, oil pump, and low oil warning system.
The oil tank is attached to the powerhead and holds
oil for delivery to the oil pump. Oil is gravity fed to the
oil pump via a hose. The oil pump injects oil into the
fuel line prior to the fuel pump and is driven by the
crankshaft.

Oil Flow Diagram

a
a - Oil Reservoir
b - Fill Cap
c - Oil Level Sight Gauge
d - Carburetor
e - Fuel Filter
f - Fuel Pump
3C-6 - FUEL SYSTEM
A link rod is connected between the throttle linkage
and oil pump lever. When the throttle position is
changed, the link rod rotates the oil pump valve,
which changes the fuel/oil ratio.
The oil tank is equipped with a low oil sensor and a
magnetic float. When oil level in oil tank drops to
approximately 14.5 fl. oz. (435 mL), the magnetized
float will complete the circuit between the low oil sen-
sor leads, causing the warning horn to sound.
b
c
d
i
j
g - 2 PSI Check Valve
h - Oil Pump Relief Fitting
i - Oil Pump
j - Inlet Fuel Connector
e
g
h
90-852572R1 JANUARY 1998
f