Mercury 90 Service Manual

90-830234R3 DECEMBER 1997 FUEL SYSTEM - 3C-11
Oil Injection System
Troubleshooting Chart
(Models with Warning Module)
Troubleshooting the Oil Injection
System
If a problem occurs with the oil injection system and
the warning horn sounds in a pulsating manner, stop
engine and check if problem is caused by (1) low oil
level – 1 quart remaining, (2) the oil injection pump,
or (3) a faulty warning module.
1. Open the engine cowling and check oil level in
engine reservoir. If oil level is approximately one
quart or less, the problem is low oil level. Add oil
to reservoir.
NOTE: There is a safety reserve of oil left in the reser-
voir after the low oil warning is sounded. There is
enough oil for approximately 50 minutes of full
throttle operation on four cylinder engines and
approximately 1 hour of full throttle operation on
three cylinder engines.
2. If there is more than 1 quart of oil in the reservoir,
then the problem may be in the oil injection pump.
DO NOT run engine on straight gas when a prob-
lem may be in the oil injection pump. Engine can
be run by connecting a remote fuel tank of 50:1
gas and oil mixture to engine.
Troubleshooting Chart
PROBLEM: Warning horn does not sound when ignition key is turned to “ON” position.
POSSIBLE CAUSE CORRECTIVE ACTION
Horn malfunction or open (TAN) wire between horn and engine Disconnect tan lead from main engine wiring harness at termi-
nal block on engine. Ground this tan lead to engine ground.
Warning horn should sound. If not, check tan wire between
horn and engine for open circuit and check horn.
Warning Module Check if all warning module leads are connected to harness
leads. If so, warning module may be faulty.
Using incorrect side mount remote control or ignition/choke
assembly.
Refer to Quicksilver Accessory Guide for correct components
PROBLEM: Warning horn stays on when ignition key is turned to “ON” position.
POSSIBLE CAUSE CORRECTIVE ACTION
Engine overheat sensor If horn sounds a continuous “beep”, the engine overheat sensor
may be faulty. Disconnect overheat sensor (BLACK Wire) and
turn ignition key to “ON” position. If horn still sounds a continu-
ous “beep”, the warning module is faulty. Replace module and
retest. If “beep” does not sound, then engine overheat sensor is
faulty. Replace and retest.
Warning Module If horn continues to sound on intermittent “beep”, the warning
module is faulty or oil level is too low.
PROBLEM: Warning horn sounds when engine is running. Oil level in engine reservoir is full.
POSSIBLE CAUSE CORRECTIVE ACTION
Defective low oil sensor Disconnect both low oil sensor leads (LIGHT BLUE) from bullet
connectors. Connect an ohmmeter between leads. There
should be no continuity through sensor. If continuity exists, sen-
sor is faulty.
Drive system of oil injection pump Refer to page 3C-9, “Oil Pump Test” to determine if oil pump is
operating properly.
Warning Module Replace warning module.

Mercury 90 Specifications

General

Brand	Mercury
Model	90
Category	Outboard Motor
Language	English