Fuel pump/carburetor questions

I made an attempt at getting my r-176 Fire truck running yesterday for the first time in I am not sure how many years I think probably atleast 3. I rebuilt the carb and installed a pertronix kit. I cranked and crank (giving breaks for the starter to cool off) and has it stutter a couple times and almost come to life once but no go before the battery was too weak to get a good crank. BD-308 engine by the way with Holley governed 2 barrel carburetor.

There's one port on the carburetor with a t-splitter one side goes to the distributor but the other was open I am not sure where it used to go but assuming it shouldn't be open to atmosphere, I plugged it up temporarily and if I don't find something (a hard line with flare fitting) that should go somewhere I will just get rid of the T and eliminate the extra hole.

Well anyway to my main question. I do not have the gas tank hooked up yet because who knows whats in there. I took the inlet side hose off the fuel pump and just ran a hose down to a quart jar of gas. What surprised me was that I went through about 2-2.5 quarts of fuel this way. There is only so much space in the fuel lines and fuel bowl on the carb so I have to assume I am leaking fuel to the crankcase. I pulled the dipstick and smelled it and I didn't smell gas but having just cleaned the carb I'm not sure my nose was very sensitive to that smell at the time. There is no return line to the fuel tank that I can see so I assume the pump just makes minimal pressure and the float is supposed to stop any excess fuel from coming up the line once the bowl is full, correct? Do these fuel pumps have the ability to fail in a manner that allows fuel to leak into the crankcase directly at the pump? Or should I pull the carb and relook at the float?

Completely disconnecting the fuel line and then filling the carb bowl via the vent tubes adds enough fuel to see if the thing will start and run. A quart container isn't big enough to check things out for a longer run.
I usually use al least a 2 1/2 gallon can.
Today's gasoline makes short work of anything rubber. Neoprene appears to be no longer good enough.
If you insist on using a mechanical pump you may need to retrofit to ethanol-friendly parts.
Yes, diaphraghms can rupture and send gasoline to the crankcase.
These old IHCs suck fuel like there's no tomorow, especially a big one like that.

Completely disconnecting the fuel line and then filling the carb bowl via the vent tubes adds enough fuel to see if the thing will start and run. A quart container isn't big enough to check things out for a longer run.
I usually use al least a 2 1/2 gallon can.
Today's gasoline makes short work of anything rubber. Neoprene appears to be no longer good enough.
If you insist on using a mechanical pump you may need to retrofit to ethanol-friendly parts.
Yes, diaphraghms can rupture and send gasoline to the crankcase.
These old IHCs suck fuel like there's no tomorow, especially a big one like that.

My 5 gallon can was empty so I had to steal gas out of the motorcycle thats why I only used a quart can. I really only wanted to hear it run before I start digging in to things deeper so I figured a quart would be more than enough I figured the 308 would be a gas guzzler but not when its not even running

I am not set on keeping the mechanical pump but that is what is on there now and if it ain't broke...

I'll take another look at the float followed by pulling the pump if need be. I have a hard time believing the diaphram is ripped though as it still is filling the carb bowl.
I think i may have a fuel pressure gauge kicking around I will see if its making correct pressure. (5psi I think I read somewhere?)

The vac line that runs to the dist is for the Gov if the unit is still on the engine, No Vac advance on that engine. I don't remember if the carb had a gov section built on it or if it was a separate set of throttles in a casting under the carb on that engine. I know the 282 had the separate throttle. Anyway the open line would have connected to the gov diaphragm.
Todays gas is ment for pressurized systems. My BLD 269's (precursor to your 308) will start fine as long as they don't sit more than a week, after a week I find all the gas has evaporated and I need to re-prime the carb.
Then and Now will do a bang up job on a fuel pump rebuild, and with components to withstand todays gas. I had mine to them on a Thurs. and it was back in my hands on Mon afternoon, half a continent away.

I recently drove a S Series School bus about 10 or 15 miles using a five gallon can of gas in the bus seat and a boat fuel transfer hand pump to pressurize fuel to carb.
It was a jerky ride for sure but I made it.
It must have a similar motor (big straight six) to yours and CB's.
That thing swallowed gasoline. The bus had sat for years at a wrecking yard. It was "do or die" if I wanted it, though.
When the fuel mix went wrong it backfired out the exhaust. Cars that were tailgating me suddenly flipped u turns.
All in all pretty hilarious.