Ethanol fuel eats up rubber. If you have any rubber sections, I’d start by replacing them. Typically though fuel usually leaks, not pulling air. That’s a new one to me. I’d question my fuel pump as well since that has a rubber diaphragm typically.
My 2 ton folding crane only takes about 3-4 foot (square) area of the garage. A stand is a must as the engine will be mounted there likely for awhile. A crane you may be able to borrow if you buddy up with a few locals.