Some acclarations, been in the transition process between non E fuels and E8 fuels, soon after E8 fuels were locally introduced started giving probelms such as internal fiberglass tanks begining to leak, fuel spills and all sorts of rubber, plastic component deteoration.
Found that when removing fuel pump diaphragms in good working order for internal reed valve inspection and cleaning won't fit/sit again on it's base due to being extrmely warped, elongated & ballooned, this problem was not experienced with non E fuels whatsoever. If you?re the kind of boater that likes changing complete fuel pump won't see what's been pointing out.
Don't buy that US fuels are different to ours, all fuels must meet international standars, if yours are so special why don't we have problems with imported US cars while using our E8 fuels, besides all are fuel injected, don't have interal diaphragms on injectors and consequently trouble free issues with E fuels.
Ondarvr, you definitely like seeking 3 feet to a cat, like adding extra information to give some sort of tech emphasis to hold your post that's been pointed out as not being so. Now let's blame E fuel vapor lock inside fuel pumps for premature diaphragm deteoration. The more fuel and running time pumped throughout any mechanical fuel pump, will detreorate internal diaphragm much faster than when sitting dry and solely refreshed by fuel vapors hidden inside pump. Sorry, you blew it on this one.
Having 55 years of experience with carbed engines, did you found warped, elongated diaphragams, rubber o'rings that didn't sit well once removed and re installed where originall seated ? or just went installing new flat diaphragm or complete new fuel pump and voil?, problem solved.
In my particular case this vapor lock abberation, will not be given as mentioned, soon after fuel line is disconnected from OB, a spare female connector is hooked onto engine's male connector to keep fuel valve pin opened. Can run OB for extended time period while being flushed and consequently carb sucking all fuel found inside fuel pump lines, fuel pump itself along carb till OB drops dead. Fresh air entering through female connector while pin is kept opened will have 0 restriction as for the carb to suck fuel remains while OB is flushed at fast idle.
We won't possibly be in the least accordance with E fuels and diaphragms, o'rings related premature detereoration issues, seems we have excesively high jacked OP post. Don't forget doing the o'ring E - Non E fuel test and reach your own conclusions.
Happy Boating