Ethanol blended fuels, known as E10 or E15, have become increasingly common at gas stations across the United States. While mixing 10-15% ethanol with gasoline has been done to promote renewable fuel sources and reduce dependency on oil, boaters need to understand how these ethanol blend fuels can impact marine engines, specifically Volvo Penta models.

How Ethanol Impacts Fuel Systems

Ethanol is hygroscopic, meaning it easily absorbs water from the air. As it absorbs this moisture, it displaces any water already accumulated in the gas tank. This water-laden ethanol fuel can corrode and damage fuel system components not designed to withstand regular water exposure.

Fiberglass fuel tanks are not immune from potential ethanol corrosion over time. If any section of the fuel system contains metal components, such as a fuel filler neck, vent lines, fuel pickup or fuel filters, these areas are also susceptible to degradation from ethanol fuels.

Damage may not be immediately apparent, but can suddenly appear after prolonged use of ethanol gasoline. Pitting or leaks can develop, which could lead to safety hazards or engine performance problems if not caught early.

Potential Issues for Outboard Motors

For outboard motors, such as those manufactured by Volvo Penta, there are some additional vulnerabilities to ethanol fuels.

Portable marine fuel tanks left with ethanol blended gasoline for storage over longer periods are at very high risk for gathering moisture, which can then flow through to the engine when used next.

Likewise, built-in fiberglass fuel tanks in boats are subject to condensation buildup during storage that ethanol willmobilize faster than pure gasoline.

Due to boat design, engine components like the fuel pump, fuel injectors, seals and fuel filter will be exposed to any water or contaminants first before combustion occurs. Ethanol may loosen any built up residues or debris present, sending it directly into precision engine parts.

Fuel line deterioration is another concern unique to outboards. Any rubber or plastic components could be degraded from ethanol exposure and spring unexpected leaks. Brass or aluminum carburetors are also vulnerable to erosion from these fuels.

For two-stroke outboard motors, common in smaller motors, oil injection systems can clog more easily when attempting to inject oil into ethanol gasoline.

Volvo Penta’s Stance on Ethanol Fuels

Overall, Volvo Penta states that their engines meet all US and EU emission regulations, even when using standard E10 pump gasoline. So while their modern outboards are designed to withstand some ethanol exposure, they do not recommend using any gasoline with greater than 10% ethanol.

The engine manufacturer indicates that E15 or E85 ethanol blend fuels, or any mix exceeding 10% ethanol for marine use, can void any warranty and damage components as discussed above.

Guidelines When Using Ethanol Fuel in a Volvo Penta Motor

To minimize risks when an ethanol blend is your only fuel choice, follow these guidelines:

  • Use a 10 micron water-separating fuel filter specifically designed for ethanol fuels. Change it more frequently than recommended for gasoline alone.
  • Consider adding a fuel stabilizer at the rate recommended for ethanol blend fuels before off-season storage.
  • Drain portable tanks after each trip or fill up rather than leaving ethanol fuel sitting.
  • Inspect all fuel hoses, gaskets, seals and lines regularly for cracks or soft spots. Replace any degraded components.
  • Use extra caution when filling tanks to avoid moisture intrusion which ethanol will absorb faster.
  • Verify marina or filling station tanks are clean and water-free when fueling up.
  • If evidence of clogged filters, sticking injectors or performance problems arise, drain the entire fuel system and start over fresh.

While ethanol fuels do pose risks, taking preventative action can allow you to feasibly use such gasoline when required in your marine engine. Follow Volvo Penta’s fuel recommendations, utilize quality additives, and properly service your motor to achieve the most trouble-free operation.

Frequently Asked Questions:

Q: What concentration of ethanol blend fuel is safe for my Volvo Penta engine?

A: Volvo Penta states that any gasoline with 10% or less ethanol (E10) is acceptable to use. Blends higher than E10 can damage components and void warranties, so they do not recommend using E15, E20 or E85 ethanol fuel.

Q: How often should I change the fuel filter with ethanol gasoline?

A: Change ethanol fuel filters at least once a season, or every 50-60 hours of engine operation. Use a 10 micron filter made to handle ethanol fuels for best protection.

Q: Can older Volvo Penta motors handle E10 fuels?

A: Motors made before the late 1980's were not designed for any ethanol exposure. Use pure non-oxygenated gasoline to avoid issues. Check owner's manual for specifications.

Q: What problems require draining ethanol fuel from the entire system?

A: Issues like hard starting, rough idling, stalling, clogged filters or failure to start indicate moisture contamination. Draining the full fuel system helps resolve ethanol-related problems.

Q: Are fiberglass or aluminum tanks damaged by ethanol fuels?

A: While less prone to corrosion than metal components, fiberglass and aluminum tanks can slowly degrade from ethanol exposure over 5-10 years. Inspect carefully for leaks or cracks.