Description; Hose Connections; Oil Pump Drive System - Mercury 75 Service Manual

Description

CAUTION
Be careful not to get dirt or other contamination
in tank, hoses or other components of the oil in-
jection system.
CAUTION
Engines with oil injection must be run on a fuel/
oil ratio of 50:1 in the fuel tank, in addition to the
oil supplied by the oil injection system, for the
first 30 gallons of fuel. Refer to break-in proce-
dure in the Operation and Maintenance Manual.
CAUTION
If an electric fuel pump is to be used on engines
with oil injection, the fuel pressure at the engine
must not exceed 4 psig (27.4kPa). If necessary,
install a pressure regulator between electric fuel
pump and engine and set at 4 psig (27.4kPa) max-
imum.
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.
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 from approximately
80:1 at idle speed, to 50:1 at wide-open-throttle.
The oil tank is equipped with a low oil sensor and a
magnetic float. When oil level in oil tank drops to
approximately 1 quart (.95 liter), the magnetized float
will complete the circuit between the low oil sensor
leads, causing the warning horn to sound.
IMPORTANT: Warning horn is also connected to
the powerhead temperature sensor. If the warn-
ing horn sounds, either the oil level in oil tank is
low, or the powerhead is overheated.
3C-6 - FUEL SYSTEM

Hose Connections

a
a - Oil Hose Connections

Oil Pump Drive System

g
d
e
a - Crankshaft
b - Drive Key
c - Drive Gear
d - Apply Quicksilver 2-4-C w/Teflon on Both Areas
e - Driven Gear
f - O-Rings [0.739I (18.8mm) I.D. x 0.809I (20.6mm) O.D.]
g - Spacer
h - Oil Pump
i - Bolts; Torque to 60 lb. in. (6.8 N·m)
90-830234R3 DECEMBER 1997
a
a
22511
h
i
i
f
b
c
a