1999 Volvo Penta "WT" Models Workshop Manual, Page 385Get this manual
Follow "Starting Procedure" outlined in the operator's manualAlways make sure there are no gasoline fumes in the engine compartment before starting the engineOpen the compartment and use your noseDon't gambleBackfire flame arrestor must be in place and securely attached to the air intake Do not alter the backfire flame arrestorIf loose, damaged, or altered, an engine "backfire" may pass through the flame arrestor assembly into the engine compartmentIf fumes are present in compartment, fire and explosion could result