Yamaha ox66 issues

[Capt Terry]

As an update to my 5-18-18 post removing the anti-siphon valve and partially blocked air vent screen dropped the vacuum gage reading from 4"Hg after a partial throttle run to 2"Hg after a WOT run. I concur with some of these other remarks, after issues through the years I only use OEM fuel bulbs. And even with that replace them before you think you need to. Once couldn't keep my Merc running back to the ramp without continually squeezing the bulb.