"I have new (after 3 years in my ownership) air leaks in both fuel filters amounting to (air) pint(port) to a quart (stbd)or so for 3-4 hours running.
Have twin TAMD71As with independant intakes/returns from single tank (1988 Neptunus 48)
Have two Racor 900s, one per engine. Filters clean(2m)and seals changed. Vacuum guages (registering no appreciable vacuum...1 lb) removed and replaced with T handles. All surfaces inspected and cleaned. Intakes are at bottom of tanks and returns are at least a foot above. 2 ft head (min) on intakes No change. Intakes come from tank bottom of L shaped tank up 4 ft and then yhrouh a close nipple welded in tank side. Next is a short section of steel pipe, shutoffs and then short section into Racor inlets. Outlet side drops 2 ft to floor level and off to primer and then fuel pump. On shutdown we have perhaps 1/2 psi (column) at the filter and perhaps 2psi at the floor level (using a water column and rounding unmercifully) No leaks. Any suggestions or past experiences?"