Storing your Yamaha outboard engine for more than six months? Whether it’s off-season or you’re taking a break from boating, long-term storage needs to be done right — because doing it wrong can cost you big.
You don’t want to pull the cover off six months from now only to find corrosion, clogged fuel lines, or worse — an engine that won’t start.
But don’t worry — I’ve got you covered. Below is a step-by-step guide to help you store your Yamaha outboard safely and keep it in top shape, ready to roar when you return.
📦 Why Proper Storage Matters
Your Yamaha outboard is a precision machine. Leaving it unused for months without proper care can lead to:
- Fuel system issues (varnish, gumming)
- Corrosion in internal components
- Battery failure
- Damaged seals and hoses
- A frustrating and expensive springtime repair bill
The good news? With just a few hours of prep, you can protect your engine for months of worry-free rest.
✅ What You’ll Need
Before you begin, gather a few essentials:
- Fuel stabilizer (Yamaha Fuel Stabilizer & Conditioner recommended)
- Fogging oil
- Fresh engine oil and gear oil
- Grease gun and marine grease
- Water source with flushing muffs or a flush hose adapter
- Clean cloths and a mild detergent
- Battery charger or tender
- Engine cover or tarp
🔧 Step-by-Step: How to Store Your Yamaha Outboard (The Right Way)
Step 1: Flush the Engine
After your last ride, flush the engine with freshwater to remove salt, sand, and debris. Use a flushing kit or hose adapter, and let water run for 10–15 minutes.
💡 Tip: Always keep the engine running during the flush so water circulates through the cooling system properly.
Step 2: Add Fuel Stabilizer and Run the Engine
Add a marine-grade fuel stabilizer to your tank and run the engine for 10–15 minutes so the treated fuel reaches all parts of the system. This prevents the fuel from breaking down and gumming up your lines or injectors.
Step 3: Fog the Engine (if carbureted or older EFI)
While the engine is running, spray fogging oil into the air intakes. For modern EFI and 4-stroke models, refer to your Yamaha manual — some engines may require fogging directly into the spark plug holes or use different procedures.
Fogging protects internal metal parts from rust by coating them with a light oil layer.
Step 4: Change the Engine and Gear Oil
Old oil contains moisture and acidic contaminants that can cause internal damage. Drain and replace:
- Engine oil and oil filter
- Gearcase (lower unit) oil
Look for signs of water (milky oil) — this could mean a bad seal that needs attention before storage.
Step 5: Grease Moving Parts
Use marine grease to lube all grease points including:
- Steering system
- Prop shaft
- Tilt and trim pivots
- Linkages
This helps prevent corrosion and seizing during inactivity.
Step 6: Remove and Charge the Battery
Disconnect and remove the battery. Store it in a cool, dry place and keep it on a battery tender or charge it monthly to maintain lifespan.
Never leave a battery sitting uncharged for months — it may not recover.
Step 7: Protect from Moisture and Pests
Wipe down the engine and cowl with a clean cloth and a bit of mild detergent if needed. Check for salt residue or grime. Once dry:
- Cover all air inlets with breathable material (like cloth) to prevent critters from nesting
- Use desiccant bags or moisture-absorbing packs near the engine area to reduce humidity
- Cover the engine with a proper outboard cover or breathable tarp — never use airtight plastic that traps moisture
🗓️ Bonus Tip: Crank It Up Every 1–2 Months (If You Can)
If your boat is nearby and you have access to water, running the engine briefly every 4–8 weeks helps prevent gunk buildup and keeps moving parts lubricated.
If that’s not possible — don’t stress. Just follow all the steps above and you’re good.
🚀 When It’s Time to Start Her Up Again…
- Reconnect your battery
- Check oil levels
- Inspect for any visible corrosion
- Remove covers and air inlet protection
- Run the engine on a flush before heading to the water
Start slow — give your Yamaha a few minutes to warm up and reawaken after hibernation.
📝 Final Thoughts
Your Yamaha outboard is built to last — but only if you treat it right. Long-term storage isn’t complicated, but skipping steps can lead to damage, poor performance, or even total failure. This simple care routine helps protect your investment and gives you peace of mind through the offseason.
Want more tips? Check out Yamaha’s official Maintenance Matters page for helpful insights from the experts.
Until then — store smart, and happy boating when the season returns! 🌊⚓