Hi first time post 4 year driver of my mazda 1.6l 323

My water pump has been leaking so i haven't been driving my 323 till i find some time to fix it. So today after about 3 weeks of sitting in my drive way, i was going to start to change my water pump over. I started it up let it ran for about 5 minutes and it ran nice and smooth and when i switched it off there was smoke coming out of the carbie (had the air filter off at the time).

Is there something wrong or is it because of it been sitting there for 3 weeks?
I did put some additive in the fuel to clean the carbie and valves

Thanks in advance

TRev