Ethanol-blended fuels have become an automotive standard, but they pose significant challenges for older 2-stroke outboard marine engines, small engines, and high-performance boat racing applications.
Ethanol can cause fuel phase separation, corrosion, and degradation of outboard fuel lines and system components, leading to carburetor and fuel injector issues, poor engine performance, and costly repairs.
The Sierra 18-79816 Ethanol Fuel Tester is a simple yet effective tool for accurately determining the ethanol content in gasoline, ensuring that your Mercury, Yamaha, OMC, Johnson, Evinrude, Tohatsu, or other legacy two-stroke outboard engine is running on the correct fuel.
Why Test for Ethanol? Ethanol absorbs water from the atmosphere, which can separate from gasoline over time, forming water-contaminated fuel at the bottom of your fuel tank. This leads to:
✔ Hard starts and poor idling in two-stroke and four-stroke engines.
✔ Fuel line and carburetor degradation, causing leaks and engine failure.
✔ Reduced power output, especially in high-performance and racing engines.
✔ Phase separation, where water and ethanol sink to the bottom of the tank, leaving unusable fuel.
Testing your fuel before use can prevent these issues and ensure optimal engine performance.
What is the Sierra Marine 79816 Ethanol Fuel Tester? It's a clear, graduated test tube with ethanol percentage markings. It has easy-to-read measurement scale for precise ethanol content determination. Step-by-Step Instructions:
1. Fill the Tester with Water
- Locate the water fill line near the bottom of the tester.
- Pour clean water up to the indicated line. Distilled water is recommended for the most accurate results.
2. Add Your Gasoline Sample
- Slowly pour your fuel sample into the tester until it reaches the gasoline fill line (usually near the top).
- Avoid overfilling or spilling.
3. Secure and Shake the Tester
- Secure the cap tightly on the tester.
- Shake the tester gently for about 30-60 seconds to thoroughly mix the water and gasoline.
- Place the tester on a flat, stable surface and allow the fuel to separate.
4. Wait for Fuel Separation
- Let the tester sit for 5-10 minutes to allow the ethanol to mix with the water.
- The ethanol in the fuel will bond with the water, settling at the bottom of the tester.
- The pure gasoline will float on top, making it easy to read the ethanol content.
5. Read the Ethanol Percentage
- Check the new water level after settling.
- The increase in water volume corresponds to the percentage of ethanol in your fuel.
- Example: If the water level rises to the 10% mark, your fuel contains 10% ethanol (E10).
Understanding Your Results for Legacy Two-Stroke Outboards
✅ 0% (E0) – Ethanol-Free Fuel: The best option for legacy Mercury, Yamaha, OMC, Johnson, Evinrude, and Tohatsu outboards. Helps prevent carburetor clogging, fuel line breakdown, and engine stalling.
✅ Up to 10% (E10) – Common Pump Gas: Most two-stroke outboards can tolerate E10, but it's essential to use fuel stabilizers and additives to protect against ethanol-related damage.
⚠ Above 10% (E15, E20, E85) – NOT Recommended: High ethanol content can damage fuel system components, cause lean running conditions, and lead to engine failure in older two-stroke engines.
Best Fuel Options for Two-Stroke Outboards
✔ Recreational (REC) Non-Ethanol Pump Gas – The best fuel for two-stroke outboards, reducing the risk of phase separation and carburetor issues.
✔ Race Fuels – High-octane fuels provide better stability and combustion, ideal for high-performance and racing applications.
✔ Custom Fuel Blends – A mix of non-ethanol pump gas and race fuel can balance performance, affordability, and engine protection.
By using the Sierra 18-79816 Ethanol Fuel Tester, you can quickly and accurately determine ethanol content, ensuring that your two-stroke outboard or high-performance engine runs smoothly, efficiently, and reliably.
For more information or to purchase the Ethanol Fuel Tester, contact Mike at +1-714-697-1716 or email mike@buckshotracing77.com.