Probably crud in the carb; suggest cleaning everything from the tank to the jets; eg; the gas line, the gas filter, the small line from the pump to the carb; carb bowl and jets (idle and main). this should take care of it. Assuming your compression and spark are good.
Take the sender unit off the top of the tank and pump out the remainder of the gas. Be sure to use a pump that neutralizes the electric current created by pumpin. Check for any sediment buildup...If it''s bad you may have to replace the tank.
Replace all gas lines [they''re cheap and worth it].
Replace all filters and gaskets to water separater and fuel filter unit. Check the suction on the pump by pressing the primer. Remove carb and have it cleaned thoroughly by a knowlegeable mechanic. Put 5 gals of fresh gas with gas treatment in it. That should take care of it.
Did this all myself and it''s been perfect since.
Be extra careful of gas fumes and liquid. Can be intoxicating, dangerous, and as we all know highly explosive. Good Luck
We installed an electronic ignition available for the A-4 from Foley Marine at around $200 if I remember correctly and that solved all starting problems. Of course it wouldn''t cure a bad fuel scenario but turned out that wasn''t our problem. Last we heard she was still starting like a dream.
I would think that a tune up would the first thing you would try. Be sure points, plugs, wires, condensor, distributer cap, rotor, etc. are all in first class condition. These items are cheap and need to be replaced periodically anyways. If it still has trouble starting after a tune up, it is then you look at other more costly solutions.