I had the same problem with mine and the cause was too much fuel pressure. The Edlebrocks don't like much more than 5.5 to 6.0 lbs. I went to the trouble of putting in a good pressure regulator along with a good fuel line and the problem was fixed for about two weeks. Then I found I didn't have enough fuel pressure....the pump just took a poop. I went ahead and put a new AC/Delco pump in and it has worked great ever since....I don't even need the regulator with the new line and pump.