Why does my outboard start and then die?

Starts then dies · Symptom: Starts, runs seconds to minutes, then stalls.

Quick answer: Most often: tank vent closed (vacuum builds), primer bulb/check valve failing or air leak in fuel line, partially clogged filter or carb idle jet. Start here: Open vent; loosen cap — if it runs on, vent was the cause. If that doesn't fix it, work through the checks below, and see a marine mechanic if you're unsure.

Likely causes (most to least common)

Tank vent closed (vacuum builds)
Primer bulb/check valve failing or air leak in fuel line
Partially clogged filter or carb idle jet
Choke/enrichment removed too early on cold engine
Water in fuel
Idle speed set too low

Safe owner checks & fixes

Open vent; loosen cap — if it runs on, vent was the cause.
Squeeze bulb while running; if engine recovers, suspect fuel supply.
Inspect fuel line, clamps and connectors for cracks or air leaks.
Replace fuel filter; check fuel for water.
Warm up per manual before removing choke.
Idle speed check is in the manual's maintenance section; adjustment may be dealer-only on EFI.

Parts / tools

Fuel line/bulb kit, filter, screwdrivers, clear jar.

Call a marine mechanic when

Dies even with vent open, fresh fuel and new filter (fuel pump or carb); fuel leaking from bulb or fittings — stop and fix before running. If you're on the water and unsafe, call TowBoatUS/Sea Tow or the Coast Guard (VHF 16).

Sources

Values not stated here are model-specific; check your owner's manual.