The pumps are supposed to stop when a preset pressure is attained. But recently they have started to keep on "ticking". That should indicate a leak, but there isn't. Why?

...Sounds like You are discribing the Parallel DUAL Mounted 'Webro' Pulsating Pumps!? Five things could be happening! 1. The Pump is pumping AIR. Fuel level in tank is TOO low; OR pump is Mounted TOO far or TOO High from Fuel Tank 2. The Pump is building enough pressure to push Gas through the Carb Float 'Needle Seats', in which case The Carb would be Flooding. 3. The 'Diaphram' in one of the Pumps is Ruptured, this would be indicated by an INability to build up Pressure, if this is the case They will RUN forever. 4. In the case of TWIN Pumps, One Pump could be 'Stealing' Fuel from Or 'Canceling Out' the 'Effort' of the Other Pump. 5. Are the Pumps Real HOT? Could be 'Vapor Lock' OR 'Cavitation'; which is caused by a Very Low Pressure(Atmospheric), Which equates to a Very High 'Vacumn' on the Intake side of the Pumps. Check The Fuel Tank Vent for proper Breathing. Yes! As You Stated, These Pulsating Pumps Normaly will STOP when the Correct Pressure is achieved. One TEST would be to PLUG the Total Output and see if You can make them stop. Good Luck with it!...

...6. Those pumps have little soft 'Wafer' Check Valves, they could be worn and causing Internal Leakage!...

...You post Two separate threads and then Don't Check back on One of them?...

Some electric fuel pumps have an internal bypass circuit inorder to keep the cooler. My Aeromotive does this.