Gas tank vs portable in 4hp

[Ben in Beaufort]

I recently got a used 98 year 4hp that has a gas tank builtin and the connection for a portable tank. Which one does it use? and can it use both?
The hose runs from the tank to the sediment bowl bypassing the fuel pump, and the external tank connecting hose goes to the fuel pump and then to a nipple at the top of the carbourator. What to do and of course I have no operator's manual. Perplexed (engine has spark and compression)

 

[tashasdaddy]

Re: Gas tank vs portable in 4hp

if i'm not mistaken it will run either way, built in tank is gravity feed, for short runs, i making a longer use the portable, with the primer bulb hose, to get the gas to the fuel pump, there is a built in filter in the fuel pump.