FORUM RULES UPDATED - The forum rules have been updated to continue to provide a friendly and safe environment for our member community. Please take a moment to review the updated rules and our terms of use and privacy policy. Click here for Forum Rules which has links to the 'terms of use' and 'privacy policy'.
Could be the poppet valve sticking, getting pressurized while running and bleeding off when shut down. Can't think of any other way of pressure build up.