BlackhawkCE

Wondering if anybody's added a pump to a jett 90. I've got a GP F-14 with a jett 90 but i've never seemed to get it to run right. I keep having the problem of fuel flow to the engine. At idle I have air in the fuel line until i advance the throttle where it seems that there if finally enough muffler pressure to keep sustained fuel flow. I changed all my fuel lines this weekend and today fired it up to test but still the same problem. I can't set my needles because of this problem so my next thought is to maybe try a pump. Has anyone tried one on this engine or have some other suggestions?