The older Avons were a problem for a while...the new ones are much better with the metal valve assembly. The inflatable rep said that it was advisable to bring it up to full pressure (11 lbs) which is indicated in green on my gauge. I checked it today about (80 in the So Cal sun) and it has moved up some but still a ways from the green zone. The gauge seems accurate so I might turn my suspicion to the pump
unless someone else with the Avon/West Marine Air 310 has experiene with it.