340 Starting issue

No I haven't figured it out yet. Put in an electrical fuel pump. Tried two ways , one with it going into the mechanical fuel pump then direct into the carb. Both would run for a few seconds then die. Thought it might be getting too much few much fuel, so I put a regulator in both ways and still getting the same thing. Put a new ballast resister in and same thing. I am about ready to raise the white flag and throw in the towel. I can't figure it out. It was running. I was able to drive it down the street and back then it just quit, and I haven't been able to get it running