Mercury V8 300 User Manual

Oxygen Sensor Socket Obtain from Local Tool Supplier
a - O2 sensor connector on the engine harness
b - Cable tie securing the O2 sensor harness to
the connector
c - Cable tie securing the O2 sensor harness to
the CPS leg of the engine harness
d - O2 sensor
O2 Sensor Installation
1. Ensure that the O2 sensor sealing washer is installed on the sensor and is in good condition.
2. Carefully thread the O2 sensor into the exhaust tube. Use an appropriate oxygen sensor socket to tighten the sensor to the
specified torque.
Oxygen Sensor Socket
Obtain from Local Tool Supplier
Description Nm lb‑in. lb‑ft
O2 sensor 18 159.3 –
3. Connect the O2 sensor harness to the engine harness. Route the harness as shown in the preceding illustration.
4. Secure the O2 sensor harness to the connector with a cable tie.
5. Secure the O2 sensor harness to the CPS leg of the engine harness with a cable tie.
Pitot Pressure Sensor
The pitot pressure sensor measures the force of the water at the front of the gear housing. The sensor converts this pressure to
a voltage that is read by the PCM. The PCM uses this voltage signal to determine boat speed.
The pitot pressure sensor is located on the port side of the engine, near the flush hose and behind the intake runner.
Pitot Pressure Sensor Test
Monitor the pitot pressure (data item PitotPres_ADC, measured in counts) on the CDS G3 Live Data screen.
CDS G3 Interface Kit
8M0138392
If the counts do not increase as boat speed increases, shake or move the sensor harness and connector. If the speed begins to
change, look for a broken, loose, or corroded wire.
Continue testing with the engine OFF:
1. Disconnect the engine harness connector from the sensor.
2. Visually inspect the sensor pins and the wires coming from the engine harness connector. Look for broken, bent, or
corroded pins at the sensor and loose, broken, or corroded wires at the engine harness connector.
3. Check the resistance of the pitot pressure sensor between pins A, B, and C.
a -
Pin A
b - Pin B
c - Pin C
d - Pitot pressure sensor
DMT 2004 Digital Multimeter 91‑892647A01
a
b
c
d
67402
a
b
c
17006
d
Sensors
Page 5A-36 © 2018 Mercury Marine 90-8M0146617 eng JULY 2018

Mercury V8 300 Specifications

General

Brand	Mercury
Model	V8 300
Category	Outboard Motor
Language	English