Why does my outboard bog or stall when I throttle up?

Stalls or bogs when throttling up · Symptom: Idles OK but stumbles/dies on acceleration.

Quick answer: Most often: fuel starvation: clogged filter, vent closed, kinked line, weak bulb, gummed carb main/accelerator circuit, water in fuel. Start here: Open vent, straighten hose, pump bulb while accelerating — improvement = supply issue. 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)

1. Fuel starvation: clogged filter, vent closed, kinked line, weak bulb
2. Gummed carb main/accelerator circuit
3. Water in fuel
4. Fouled plugs
5. Fuel pump fault (dealer)

Safe owner checks & fixes

1. Open vent, straighten hose, pump bulb while accelerating — improvement = supply issue.
2. Replace fuel filter.
3. Check fuel for water.
4. Replace plugs.
5. Still bogging: carb or fuel pump service by mechanic.

Parts / tools

Filter, fuel line, plugs.

Call a marine mechanic when

Persists after filter, fuel and plugs; any fuel pump replacement on EFI (high-pressure fuel); suspected carb accelerator circuit. If you're on the water and unsafe, call TowBoatUS/Sea Tow or the Coast Guard (VHF 16).

Sources

• https://cf.hondappsv.com/files/OP/OP000105GLOBAL/Trouble%20shooting_BF75-100_EN.pdf
• https://boattest.com/article/coping-wethanol-enhanced-gasoline
• https://www.mercurymarine.com/us/en/service-and-support/owners-resources/maintenance-made-easy/fuel-basics

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

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