The Relationship of Gasoline Diolefin Content to Deposits in Multiport Fuel Injectors

The dioiefin content of unstable gasolines has been implicated in the restriction of multi-port fuel injectors by deposits. Vehicle tests of the effect of adding a diolefin mixture to a stable (olefinic) gasoline indicated that a deposit-producing gasoline resulted. Laboratory oxidation tests showed that addition of a “dienophile” to an unstable gasoline significantly reduced deposit formation, increased oxidation stability, and reduced gum formation. Additional vehicle tests with a dienophile-treated fuel showed that some injector deposits were reduced, but new deposits occurred in other areas of the fuel system. Apparently, diolefins can be a factor in producing plugged fuel injectors, but other fuel factors are also likely to play important roles whether diolefins are present or not.