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Solved problems · Dinghy · Crew answer

Why won't my outboard start after it has been sitting?

Most outboards that won't start after sitting have stale fuel or a gummed-up carburetor. Check the kill switch lanyard, fuel and spark before taking anything apart.

Symptom

A gas outboard that ran fine before storage cranks or pulls over but won't start, or starts and dies, or runs only on choke.

Likely cause

Gasoline breaks down over weeks to months, and ethanol blends absorb water. Stale fuel leaves varnish that clogs the small jets in a carburetor. Water in the fuel, a clogged fuel filter, a fuel tank vent left closed, a pinched or cracked fuel line, a fouled spark plug, a weak battery on electric start, or the kill switch lanyard not fitted are all common.

Stop now if

You smell strong gasoline fumes, see fuel leaking, or the motor is on a dinghy in a confined space. Stop, ventilate and fix the leak before cranking. Never run an outboard out of the water without a flushing attachment, and never run it in a closed space.

The fix, in short

  1. Check the simple things. Make sure the kill switch lanyard clip is fitted, the motor is in neutral, the tank vent is open and the fuel line is connected and primed.

  2. Replace the old fuel. Drain old fuel from the tank and, if the motor has one, the carburetor float bowl, and refill with fresh fuel. Old fuel that smells sour or looks dark is a likely cause.

  3. Check the filter and lines. Look for water or debris in the fuel filter, and check fuel lines and the primer bulb for cracks or soft spots.

  4. Check the spark plug. Pull the plug and look for wet, fouled or worn electrodes. Replace it if in doubt.

  5. Clean the carburetor. If fresh fuel and a new plug don't help, the carburetor jets are probably varnished. A dealer can clean or rebuild it.

  6. Prevent it next time. Use fuel stabilizer and fresh fuel, and run the carburetor dry or drain it before storage as the engine manual recommends.

Written by Sailor Cruiser crew. General guidance, not an inspection of your boat.

Equipment involved

  • Dinghy outboard: Small gasoline outboard, fuel tank and line, primer bulb, carburetor, spark plug and kill switch

Related guides

Sources

Background reading we checked while writing this answer. The wording above is our own.

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