primer check valves

[flattop1]

85 evinrude 90 hp manual says to test primer check valves. I am unsure where they are or if they are in the little pipe fittings.
manual also says they cause rough idle and loss of high speed rpm.
can they simply be plugged?

 

[emdsapmgr]

They are there to improve engine idling. Still sold today. If you have originals in that block, likely you should consider just replacing them.