Fuel Tanks & System

If your boat has an engine, it needs adequate nutrition—it needs a place to store its fuel and a way to get the fuel to the engine—your engine needs a fuel system.
Marine fuel tanks fall into one of two categories: permanent or portable. Stern drive and inboard boats are equipped with permanent fuel tanks that are usually located under the deck, and aren’t meant to be removed.
On the other hand, portable fuel tanks are…well, they’re portable, so you can take them off of the boat for refueling. You can extend your boat’s operating range by simply adding more portable tanks (within reason, of course). Smaller outboard-powered boats commonly use portable fuel tanks.
Permanent Fuel Systems
A typical permanent fuel system consists of:
  • Fuel tank (usually made of aluminum, fiberglass, or plastic)
  • Hold-down straps (to secure the tank)
  • 1 ½” deck fill fitting (including the gas cap)
  • 1 ½” fuel fill hose (from the deck fill fitting to the fuel tank)
  • Thru-hull vent fitting (allows fuel vapors to vent to outside of the boat)
  • 5/8” vent hose (from the fuel tank to vent fitting)
  • 3/8” fuel hose (from the fuel tank to the engine)
  • Primer bulb (manual hand pump from fuel tank to engine--outboards only)
  • Fuel fittings (to attach hoses to the fuel tank)
  • Hose clamps
  • Fuel sending unit (electrical device that tells the gas gauge how much fuel is in the tank)
Permanent fuel systems are one of those “out of sight, out of mind” things on your boat that are often overlooked during routine maintenance.
Potential problem areas include:
  • Dropping the gas cap into the water during refueling
  • Hoses and primer bulb(s) (especially those exposed to the elements) tend to crack and develop leaks over extended periods of time
  • Fuel gauge malfunction may indicate an issue with the fuel sending unit
Portable Fuel System
A portable fuel system is relatively simple, usually made up of:
  • Portable fuel tank (steel or plastic)
  • Fuel hose (from the fuel tank to the outboard engine)
  • Quick-disconnect fuel fittings (one on the engine end of the fuel hose, one on the gas tank end of the hose)
  • Primer bulb (an inline, manual pump used on most outboards)
  • Tie-down strap (to hold tank securely to the deck while underway)
Portable fuel tank systems are easy to inspect and service, but have their own issues:
  • Debris or rust in the portable tank
  • Fuel hose and primer bulb deteriorating from exposure to the sun, cold, etc
  • Quick-disconnect fitting(s) developing leaks from repeated use (connecting & disconnecting)
When you’re filling portable tanks, always place the tank on the ground and keep the gas pump nozzle in contact with the portable tank. Never put gas in portable tanks while the tanks are in the car or truck—static electricity can build up, creating a spark and fatal explosion.

Permanent or portable fuel tank systems will serve your engine well—if you provide a moderate amount of upkeep—and strand you on t