Mercury 75-115HP 4-Stroke EFI Starter Motor 12V 14-Tooth

Overview

High-torque 12V reduction starter for selected Mercury four-cylinder EFI four-stroke outboards from 75HP to 115HP. The unit uses a 14-tooth pinion and must be matched by engine serial number, original Mercury reference and physical configuration before installation.

Technical specifications

Engine compatibility and OEM references

• Mercury 75HP EFI four-stroke, four-cylinder — selected serial 1B759588 and later.
• Mercury 80HP EFI four-stroke, four-cylinder — selected serial 1B759588 and later.
• Mercury 90HP EFI four-stroke, four-cylinder — selected serial 1B759588 and later.
• Mercury 100HP EFI four-stroke, four-cylinder — selected serial 1B759588 and later.
• Mercury 115HP EFI four-stroke, four-cylinder — selected serial 1B759588 and later.

Mercury references to compare: 50-879345T77, 50-879150A85, 8M0038387, 897525T03 and 897525T05.

Do not order from horsepower alone. Confirm the serial-number plate and original starter reference because Mercury used different starters within similar horsepower families.

Installation and pre-fit checks

• Disconnect the battery and isolate the positive lead before removing the starter.
• Compare the 14-tooth pinion, nose length, mounting holes, rotation convention and terminal orientation with the original unit.
• Load-test the battery and check positive and earth-cable voltage drop, starter relay/solenoid output and flywheel ring-gear condition.
• Clean the engine mounting face and torque bolts and cable terminals to Mercury specifications.
• Verify clean engagement and immediate disengagement after installation; do not use prolonged cranking cycles.

Frequently asked questions

Q1. Does it fit every Mercury 75-115HP four-stroke?
No. It is for selected four-cylinder EFI engines, generally from serial 1B759588 onward, and the original reference must match.

Q2. Will it fit Mercury two-stroke engines?
No. This configuration is intended for the listed four-cylinder EFI four-stroke family.

Q3. How many teeth does the pinion have?
The replacement uses a 14-tooth pinion; compare it directly with the original starter.

Q4. What can cause a replacement starter to fail early?
Low battery voltage, cable resistance, a sticking solenoid, damaged ring gear or excessive continuous cranking can overheat or damage the starter.