Mercury V8 300 User Manual

The start relay is located in the bottom of the electrical panel, at the rear of the engine.
a - Electrical panel
b - Start relay socket on the engine
harness
c - Start relay
a - PCM connector A
b - Start relay socket
c - Main power relay (MPR) socket
d - Starter solenoid
e - Starter power stud (+)
f - Hot stud (battery +)
g - Fuses ‑ 20‑amp fuse
Connector Pin Wire Color Function PCM
86
87
85
30
59637
30 Red 12 V battery power (+) –
85 Red/blue Fused (20 A) 12 V power (+) –
86 Black/blue Start relay control AE2
87 Yellow/red Starter solenoid power (+) –
MPR 86 Yellow/purple MPR control signal AA2
MPR 87 Red/white Switched 12 V power (+) –
a
b
c
66554
105A
105B
109B
109A
106B
RED/BLU
RED/WHT
RED/BLU
RED/WHT
RED RED RED
YEL/RED
YEL/RED
BLK/BLU
BLK/BLU
RED
YEL/PPL
YEL/PPL
RED
RED
20A
A1
A2
A3
A4
A5
A6
B1
B2
B3
B4
B5
B6
C1
C2
C3
C4
C5
C6
30
8586 87
30
8586 87
H4
A2
E2
A1
A
B
C
D
E
F
G
H
1
2
3
4
A
B
C
D
E
F
G
H
H
A
4
1
87
30
8685
B6 B5
B4
B3
B2
B1
C6
C5
C4
C3 C2
A6 A5 A4 A3 A2 A1
C1
87
30
8685
g
a
b
c
d
e
f
65462
Actuators and Relays
90-8M0146617 eng JULY 2018 © 2018 Mercury Marine Page 5B-7

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