Most recreational gasoline now contains ethanol (usually E10). Ethanol attracts water, can cause phase separation, degrade older rubber and plastic components, and leave deposits that clog filters and injectors. Proper fuel system care prevents expensive repairs and downtime.
Why Ethanol Causes Problems on Boats
- Water absorption leads to phase separation (ethanol/water layer sinks).
- Corrosion of metal parts and degradation of seals, hoses, and gaskets.
- Varnish and gum formation during storage.
- Clogged fuel filters and injectors.
Practical Prevention Steps
- Use a quality marine fuel stabilizer every time you fill up, especially before storage. Run the engine afterward so treated fuel reaches the entire system.
- Keep tanks as full as practical during storage to minimize condensation.
- Change fuel filters regularly — more often if you notice water or debris. Use water-separating filters where possible.
- Inspect and replace aging hoses and seals with ethanol-compatible marine parts.
- Consider a fuel additive or treatment formulated for ethanol and marine use.
- Drain or treat old fuel rather than leaving it for long periods.
During Storage and Winterization
Stabilize a full tank, run the engine, and address any water in the fuel system before laying the boat up. Pair this with your normal engine winterization (oil change, fogging, etc.).
Shop fuel pumps, filters, stabilizers, and related engine service parts in our engine and fuel system collections. Regular filter changes and the right additives are inexpensive insurance.
For technical details on marine fuel systems, consult your engine manufacturer’s manuals and ABYC guidelines.