As you know getting my old minnie telemaster ready to go, put on outside table, had the TT10 Davis head, ran like a dream, next day decided to do a re check before flying engine starts on prime and dies.checked tank and lines (3) engine feed, fill line, that gets a plug and muffler pressure line that has a one way pressure fitting, swapped engines put in the OS 10 same issue. fuel feed fine put in cap on fill line, same issue, I pulled the muffler pressure line and tried to blow thru it no go almost no air got through it. turns out off course blocked with no air or exhaust pressure to tank impossible to draw fuel, pulled the one way pressure fitting off then connected line to tank and all is well martin
I was ready to pull tank and replace but no need now martin

no air in no fuel out (unless bladder of course)