Some good suggestions in other posts. One other thing you could try is putting the jugs in a box with a lightbulb to warm them. This lowers the viscosity of the resin and hardener making it easier for the pumps to draw.

: Has anyone else had trouble with their plunger-type epoxy pumps? I just had
: another one go bad. During the downward pump stroke, it spits a slug of
: air. There must be a bad seal or check valve that lets air in during the
: up stroke even though the pump is almost new. Is there a fix for this? For
: some reason, it is only the resin pump that I have had trouble with. I
: tried heating the resin and pump thinking that there might be some
: crystalized resin gumming things up, but it didn't help.

: Thanks,

: Jon