Mercury 9.9EH FourStroke Outboard Motor

This used Mercury 9.9EH is the short-shaft, electric-start configuration of the 9.9 hp FourStroke line, running a 15-inch shaft and tiller steering rather than the longer shafts or remote-steer setups found elsewhere in the family of 9.9 motors.

What the short shaft is for

A 15-inch shaft matches low-transom boats; on a taller transom the propeller would run too shallow to push properly. At 84 lb, Mercury lists this as the lightest configuration in the lineup, worth knowing if you're weighing a transom or need to lift the motor by hand onto a dock.

Under the cowling

It's a carbureted two-cylinder engine with CDI ignition, running the standard 2.08:1 gearcase, with trim worked by hand through a ratcheting lever instead of an electric tilt motor.

Buying it used

Because this is a used motor rather than new stock, ask about hours, compression, and the condition of the water pump impeller before relying on the listed specifications alone; impellers wear out quietly and can cause overheating if ignored for too long. Fuel-wise, Mercury calls for 87 octane gasoline, tolerant of up to 10 percent ethanol, paired with its own FourStroke 10W-30 oil.

Common questions

Does it have a pull-cord or push-button start? Push-button electric start, paired with tiller steering.

What's the gear ratio? 2.08:1, Mercury's standard gearcase for this engine.

What's the exhaust setup? It exits through the propeller hub for a quieter idle.