1005 rs vector doesnt start after engine replacement

[Sissi]

I just got my vector put together and it doesn't start. I check the carburators bottoms and in 2 of 3 was fuel but not in the third one. Why is there 2 fuel pumps to 2 carburator if there is 3rd carburator too.
And when I start without airfilter cover and spray brake cleaner to carburators the carburarors spits fuel out. And my engine room got in fire for a moment.