1972 Merc.800 fuel pump check valves

[Gomer50]

Is it possible the fuel pump check valves go bad.I have replaced the fuel pump diaphram,new bulb,new fuel lines,new gas tank,Carbs have been rebuilt several times look newer than new.No leaks that I can tell.At WOT runs okay for awhile then I need to pump the bulb a couple of times and it keeps on going ( repeat ).I do have a couple of 90 degree barbed elbows in the fuel line maybe causing some fuel restrictions.But really curious about the check valves..

 

[Barnacle_Bill]

Re: 1972 Merc.800 fuel pump check valves

Sure they can go bad. If fact Merc redesigned theirs for the square type fuel pump. It seems that ethanol was causing the edges of them to curl up. The new ones look like a flat plastic washer.