That's a new one (keeps running when starter is on)? Anyhow from what you say sounds like a bad glow plug or no fuel. It can be a b-t working with an old engine since you have no idea what previous owner as done. Any glow plug should usually work as long as you know it glows brightly. With needle valve opened about 2-1/2 turns choke it till you see fuel at carb. Connect glow plug but do not use starter at this time. Hand start carefully ( use a chicken stick). It should at least fire several times maybe even start. At this needle setting it should be a bit rich so adjust for smooth running. If it quits then you may have a fuel problem or clogged fuel valve. If running decent then try adjusting idle. You failed to mention what engine you have but if air bleed open air hole slightly to lean out close to richen. If separete idle screw close to lean open to richen.Tuning an engine takes experience so get help if possible.