wrote

PS. Did I mention that I think the problem with hunting on my 2gm20
was with a faulty valve on the return line? On some versions of the
2gm and other Yanmars they "T"ed the return line and sent some of the
fuel back to the primary via a one way valve (a BB and seat). If that
valve leaks it makes enough vacuum to pull some fuel out of the filter
and you get air in the system... I removed the valve and took out the
"T" and that seems to have solved things. I'm sure that Yanmar went
to the trouble of doing things that way for a reason but so far I
can't see any difference in performance...

Very interesting. All the fuel on my 2QM (earlier version) goes back to the
filter and it works fine.

--
Roger Long