q about factory in floor fuel tanks

[grown in Tx]

Just wondering how it works. The one in my boat is aluminum and not hooked up. It is maybe 4'x1x1. I use 2-6.5 gallon plastic tanks right now that equals to allot of weight in the back and then only on one side as the first tank empties.
From what i understand the outboard has its own fuel pump so the tank doesn't require one?
I am thinking there should be only 3 hoses on the tank, a big fill hose, a smaller maybe 3/4 inch vent hose and there should be a third going to the motor?
The fuel sending unit is not there at all and I'm not sure how to go about asking for the right one for this tank that is foamed into the floor of the boat, while It would be nice to have the fuel Guage working, it's not really needed, I'll be taking an extra 5 gallon tank anyway.

[Robalo]

Depends on type of boat as to how tank is set up. Yep, 3 lines-a fill line, an overflow line and a fuel line to motor (two if twins). My Robalo- the 120 gallon tank is in a coffin box, under the console and floor. It originally was foamed in using a closed cell foam so it doesn't sponge fuel/water. It is costly to remove and time consuming-you literally have to saw it out using a cable to cut thru the foam. replacements are strapped in unless you want to go thru the foam stuff again eventually. My Tank is aluminum. Replacement tank I had coated to impede corrosion. Plan on $4000 or so total cost.

[grown in Tx]

Damn, 4k. I don't think it needs to replaced, just cleaned out. I sucked all the water and fuel out of it with a hand pump. The previouse owner said he couldn't get it to work right. I was planning on cleaning it out with some sort of foaming degreaser, Replacing all the hoses and trying that.
So does there still need to be the bulb on the fuel line at the motor like with the external tanks? Or is there some sort of fuel pump involved to get the fuel to the motor?
Best i can tell is a 20gl tank that sits between the consoles and starts at the bow seat. The boat is a 1977 17' proline.

[Root Canal]

I would says Yes. You still need a squeeze bulb before the motor.

[OR19]

If it's the original tank it probably needs to be replaced. Pressure test it before you spend any money on it. You do need a bulb.

I replaced the one in my 91 or 92 whaler(never can remember) about 2011, it was coated aluminum and foamed in, but the salt eventually won...Robalo is correct it was pricey, I can't recall exactly but the 76 gallon tank was about $1200 and another 2k + to pull and replace. The 19ft Outrage I have didn't come with the screw in floor above the tank. Had to saw along a seem to get it out...I've got screws now.

[grown in Tx]

Pursue test, got it. I don't want to spend allot on this boat, i picked it up for 1k and put 600 in it. I'll be able to finance a nice used boat next year. Unless i can make something happen in this star tourny. Thanks for the help.

[Robalo]

Grown: I wouldn't change your current sent up for a 77 Proline. Next you'll find the transom is bad and that'd be after sinking $3-4k on a gas tank replacement. Pressure test but how can you do that if tank is under floor without cutting floor to ensure you plugged the holes? I'd run the old boat using portable tanks then sell it to someone and buy a new rig.