Cruiselog Meter; Testing; Vacuum Gauge; Speedometer - Mercury 305 CID Service Manual

Cruiselog Meter

TESTING

Connect jumper wire from negative (–) battery
1.
terminal to negative (–) gauge terminal.
Connect jumper wire from positive (+) battery ter-
2.
minal to positive (+) gauge terminal.
Observe gauge run indicator. If indicator is turn-
3.
ing, gauge is operable; if not, replace gauge.
a - Indicator
Index
4D-4 - INSTRUMENTATION

Vacuum Gauge

TESTING
Disconnect vacuum hose from engine. Connect
1.
service vacuum gauge to engine and record en-
gine vacuum readings at idle, 1000, 2000 and
3000 RPM. Reconnect vacuum hose and com-
pare vacuum gauge readings (at specified RPM)
with service gauge readings. Readings should be
within 3 inches of vacuum of each other.
IMPORTANT: Make sure that vacuum hose be-
tween gauge and engine is not leaking and that
all connections are tight.

Speedometer

TESTING
IMPORTANT: When testing speedometer gauge
72752
for accuracy, the air supply used for the test must
be regulated to the specified air pressure. Do not
apply excessive air pressure to speedometer
gauge.
Apply air pressure directly to speedometer gauge
1.
(specified in chart) and note gauge reading. Light
tapping of pressure gauge is required during ac-
curacy check.
If gauge readings are not within specifications,
2.
gauge is defective.

CALIBRATION CHART

Air Pressure Guage
a
72753

Tachometer

TESTING
Connect a service tachometer to engine and
1.
compare readings.
Replace if not within specifications.
2.
Tachometer
6000 RPM
8000 RPM
Speedometer Gauge
PSI MPH (km/Hr)
5.3 20 2 (32 1.6)
27.8 45 1 (72 1.6)
Allowance
150 RPM
200 RPM
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