It could be a number of things;
[*] Does it backfire through the carb when it shoots gas?
1) It could either be flooded or the timing has jumped. After cranking for a few moments, open the throttle plates and look for puddled gasoline on the plenum (intake manifold) floor. If there is a large puddle, either the carb float is stuck or the carb bowl plugs are leaking. Make sure you also check the choke and choke pull-off for proper operation.
2) Check static timing by setting the timing mark(s) at TDC and seeing if the dist. rotor points to No.1 on the dist. cap.
[*] Make sure the battey is fully charged. Most ECM's (if you have a feedback carb.) need to read at least 12V for reference voltage for proper operation.
Just a couple of suggestions, but will give you a place to start.