My first suspicion is that the mixture ratio is off. Early in my building process I had to throw out two batches of epoxy when my pumps 'burped'. Better to start over than to have to remove wet (uncured) resin. I gave up on the metered pumps, and went out and purchased medicine dosing cups in quantity. These cups are inexpensive, and available in 1 ounce and 6 ounce sizes. They make keeping the proper mix ratio quite simple. In addition, you can mix up a very small quantity of epoxy for small jobs, like a single panel joint or a coaming reinforcement. Saves on the resin in the long run, and the cost of the mixing cups is alot less than a quart of epoxy.