The Carter YF was last produced approximately 35 years ago, so "young they are not".
Today, the YF has 3 major issues, none of which are the fault of Carter, and a few minor issues which may be attributed to old age.
(1) The use of a fuel valve from a FLAPS kit which has too large an orifice and causes flooding
(2) The neoprene style accelerator pump, which will harden after being place in modern fuel IF ALLOWED TO SIT DRY!!!
(3) Dr. Goodpliers, and all of his descendants, who believe that all components of all YF's are completely interchangeable!
In general, the diaphragm will NOT give problems if the engine is started sufficiently often to keep fuel in the bowl. Let it dry out, and I know an excellent source of rebuilding kits!
Jon
