1988 Johnson Evinrude "CC" 9.9 thru 30 Service Manual, P/N 507660, Page 48Get this manual
Fuel Requirements
Minimum Octane Models Recommendations Pump Posted "RON"
See fuel classifications below
Preferred Fuel: Any regular unleaded, regular leaded, or premium unleaded gasoline having the recommended octane rating and not extended with alcohol is the preferred fuelAcceptable Fuel: Any of the above gasolines with up to 10 maximum alcohol volume10 ETHANOL (ethyl alcohol) (may be called gasohol) METHANOL (methyl alcohol)cosolvent alcohols Unacceptable FuelDo not use any regular unleaded, regular leaded or premium unleaded gasoline having more than 10 ETHANOL or more than METHANOL even if it contains cosolvents or corrosion inhibitor and regardless of octane rating
INote Alcohol
extended fuels may result in engine running quality problems, vapor lock orfuel st arvat ion" problems, or moisture absorption (phase separation) problemsIf running quality problems are experienced, switch to gasoline without alcohol as described in Preferred Fuel