Exhaust Emission Control Systems and Vapor Lock - CRC Road Tests 690759

This paper reports the results of a series of vapor lock road tests on 26 cars (1966 models), half of which were equipped with exhaust emission control systems. The objectives of the tests were to determine the effect of emission controls on vapor locking tendencies, to study effects of fuel volatility and operating conditions on fuel system temperatures, and to study correlation of these temperatures with temperature versus vapor/liquid ratio characteristics of fuels. The data obtained show no significant difference in vapor locking tendency between the emission control equipped and nonequipped cars as groups, though significant differences are shown for some individual car pairs. An analysis is presented of the relation between fuel volatility, pump temperature during acceleration, and the onset of vapor lock.