Additionally. Although the accelerator pump squirts fuel into the inlet, the idle jet and/or main jet system could still be blocked. Some carbs take the idle jet supply from the main jet circuit so a blocked main jet will cut the fuel to the idle jet. Don't know what this Weber does. If it's giving a few coughs or showing signs of wanting to start it may just be down to the fuel pumped in when you pump the throttle. I know we're worried about the apparent lack of spark from the coil lead but as you're getting sparks at the plugs, hopefully at about the right time, it looks as if that's ok. Spark can be a bit weak when the starter is hogging all the current, that's why an engine sometimes catches the instant you let the key spring back.