carb hookup

I just got this mower, briggs engine 17hp 42a707 it does not get fuel to carb. The fuel line from the gas tank is hooked up to the bottom of pump. and the side connection is blocked with a hose and screw. This does not seem right. is it? I figured it out , but I now can not find where the vacuum line hooks up to on the engine

Mowers come in 2 varieties , gravity feed ( tank under steering wheel ) & pump ( tank under the seat ).
First one does not need a pump while the second one does .
Because of cut throat pricing engines get made with & without pumps.

So if you want good information we need to know what mower you have and the rest of the engine number,

If you go to the Briggs web page support section you can download the pats diagram for the engine that you have.
Then from there you will be able to see what part was optional for a pump equiped engine.
Some have a hole in the rocker cover, come have a take off on the dipstick tube some have a nipple screwed into the crank case.