Abstract: Intake valve deposits in port fuel injected engines are reduced by using a mixture of (a) of about 2.5 ppmw or higher of basic nitrogen in the form of an oil-soluble aliphatic alkylene polyamine containing at least one olefinic polymer chain, said polyamine having a molecular weight of about 600 to about 10,000, and (b) from about 75 ppmw to about 125 ppmw based on the fuel composition of certain oil-soluble olefinic polymers, poly(oxyalkylene) alcohol, glycol or polyol or mono or di ether thereof, non-aromatic oils or polyalpha olefins. The fuels are also compatible with carburetor and throttle body injected engines.