: I ran into the burping pump problem in the middle of laying up a carbon fibre
: rudder. You can bet I said a few choice words. I muddled through and the
: rudder came out fine.

: Afterwards I disassembled the pumps and found the problem. The epoxy had
: gotten quite gummy around the steel balls that create check-valves at the
: bottom and in the head of the pump. Consequently they were not functioning
: properly and caused the burp.

: One hour and 1/2 a gallon of lacquer thinner later they're shiny clean and
: pumping normally again. From now on I'll make it a point to clean the
: pumps before any major epoxy work.

The burping problem seems more regular on the epoxy pump, than the hardners in my experience.

If I've not used the pumps that day I always assume they will burp. I remedy this by starting with a slow stroke which
will cause the pump to burp out the trapped air first with a minute dribble of resin or hardener. I do this until I see and
feel the pumps get firm and filled with resin or hardener. Once this is done I seldom have any more burping problems.

All the best,
Rob Macks
Laughing Loon CC&K
www.laughingloon.com