Establishment of a Test Method for Fuel Pump Vapor Lock 2004-01-0991

Vapor lock of a fuel pump can cause serious problems such as engine stall or re-start delay. At present, the vapor lock performance of the fuel pump is evaluated in component tests and actual vehicle tests conducted with an environment chassis dynamo. However, these tests include several problems, including a lack of correlation with the actual market environment and poor accuracy. One characteristic of fuel pump vapor lock is susceptibility to influence from changes in the fuel temperature and ambient atmospheric pressure and from fuel property differences due to the season or geographical area. One cause of poor accuracy in traditional test methods can be attributed to the use of the fuel temperature, which is difficult to manage, as the variable.

A new test method using suction or negative pressure as a variable has been developed based on the generally known Antoine equation for the relation between the temperature and vapor pressure of hydrocarbons in gasoline. We established a judgment criterion that correlates with the market environment in order to make clear the vapor lock performance that should be guaranteed. This paper explains the new evaluation method that allows tests to be conducted with simple facilities.