System and method for testing for error conditions in a fuel vapor recovery system

A method of detecting vapor leaks and pump performance deficiencies in a fuel delivery and vapor recovery system that dispenses fuel through a nozzle and includes a vapor transfer line connected to a pump for pumping vapor from a vapor inlet in the nozzle to a vapor outlet, comprising the steps of:

• (a) connecting a pressure sensor in the vapor transfer line between the nozzle and the pump;
• (b) blocking the vapor transfer line in the nozzle so as to isolate a section of the vapor transfer line between the vapor inlet and the vapor recovery pump;
• (c) operating the pump at a selected speed so as to generate a pressure in the isolated section of the vapor transfer line;
• (d) measuring the pressure in the isolated section of the vapor transfer line with the pressure sensor and producing a test pressure signal representing the measured pressure;
• (e) inputting the test pressure signal from the pressure sensor into a processor;
• and
• (f) comparing the test pressure signal with a reference pressure to determine if a fault condition exists between the vapor inlet in the nozzle and the pump.

A method of testing a vapor recovery fuel dispenser that has a liquid dispensing nozzle and a liquid conveying line to the nozzle, a vapor return port in the nozzle connected through a vapor return line to a vapor reservoir, a valve in the vapor return line between the nozzle and the reservoir, and a pump in the vapor return line between the nozzle and the valve driven by a motor for pumping vapor through the vapor return line at a volumetric rate determined by the pump motor speed, comprising

• closing the valve,
• driving the pump with the motor at a given speed,
• measuring the pressure in the vapor return line while the valve is closed and the motor is driving the pump at a predetermined speed and storing the measurement,
• opening the valve and using the pump and motor to pump vapor during fueling operations, and
• subsequently, closing the valve, operating the motor at the predetermined speed, measuring the pressure in the vapor return line and comparing the measurement with the stored value to determine any needed re-computation of the relationship of the motor speed to the volumetric flow through said pump to assure control of the volumetric flow.