Fuel vapor leak test system and method comprising successive series of pulse bursts and pressure measurements between bursts

A leak test system for a motor vehicle fuel system that holds volatile liquid fuel for operating the vehicle, the leak test system comprising:

• a processor for establishing steps of a leak test;
• a pump for forcing air under pressure into vapor containment space of the fuel system during a leak test;
• a pump operator that operates the pump in accordance with steps established by the processor to cause the pump to create a superatmospheric pressure in the space during an initial step of the leak test, and that, after completion of the initial step, causes the pump to perform a further step that comprises forcing pulses of air into the space in a succession of pulse bursts, wherein each burst comprises a succession of individual pulses of air, and each successive burst is delayed from an immediately prior burst by a time interval substantially longer than the time intervals between individual pulses in each burst;
• and
• wherein the processor processes data corresponding to a measurement of pressure in the space after the occurrence of at least one of such bursts and as a result of that processing indicates leakage from the space.