Mercury V8 300 User Manual

Name Description Additional Comments
Ignition Spark
Activates the chosen ignition coil to allow for
testing with a spark gap tester.
Since these engine utilize waste‑spark, both leads
on the shared coil must be grounded and will fire
simultaneously.
Smart Start
Activates a start sequence, engine will crank and
start if able.
Tach Output
Sends a 3000 RPM signal on the gray analog
tachometer lead to test operation of a
tachometer.
Injector Pulse
Activates the chosen fuel injector to diagnose
functionality.
Disconnect the fuel pump and relieve fuel
pressure to prevent flooding cylinders during the
test.
Trim Relay
Activates the trim up or down relays to diagnose
their functionality.
Starter Output
Activates the start relay to crank the engine,
without applying fuel or spark.
Electronic Throttle
Control Output
Allows the ETC to be manually activated to
observe its operation with the engine off.
Advanced Sound
Control
Activates the Advanced Sound Control valve
open or closed.
With the engine running, a change in the exhaust
noise should be very apparent.
CDS G3—Diagnostics Screen
90-8M0146617 eng JULY 2018 © 2018 Mercury Marine Page 3E-3

Mercury V8 300 Specifications

General

Horsepower	300 HP
Displacement	4.6 L
Full Throttle RPM Range	5200-6000 RPM
Fuel Induction System	Electronic Fuel Injection (EFI)
Gear Ratio	1.75:1
Starting	Electric
Shaft Length	20 in, 25 in, 30 in
Warranty	3-Year Limited Warranty
Engine Type	V8
Fuel Type	87 Octane
Bore x Stroke	92 mm x 86 mm