You may not have one. If you do it would have to be located between the fuel tank and the engine. I would follow the fuel line from the engine and look in places leading back to to the fuel tank that are that are easily accessible like door panels or an inspection or deck plate.
If you don't have one I would recommend you put it on your list. Since you are running an outboard, you want the one with a see through plastic bowl on the bottom since it could save your motor and or a trip. They have pit cocks to drain any water that might separate to the bottom of the bowl like this
https://www.walmart.com/ip/Racor-10-...&wl13=&veh=sem
Not sure if your boat has a closed transom or a motor well, if a motor well, the side of the motor well where the fuel line comes out is a good place as any to mount one. If a closed transom then find a place inside the hull that's convenient to get to like behind a panel or inspection plate and away from any wires or electronics.
While you're at it, with the age of your boat which is pre ethanol, I would also consider replacing all the fuel lines with ethanol approved ones. The non ethanol lines can break down over time, collapse and restrict your fuel flow. I've seen guys spend thousands of dollars on all sorts of other stuff, only to find out a small section of their fuel line collapsed causing all their issues.
