Yes, gravity feeding of diesel fuel is legal, according to:
FMCSA regulation 393 Subpart E – Fuel Systems
- § 393.65 All Fuel Systems.
(d) Gravity or syphon feed prohibited. A fuel system must not supply fuel by gravity or syphon feed directly to the carburetor or injector.
- § 393.67 Liquid fuel tanks.
(5) Fuel withdrawal fittings. Except for diesel fuel tanks, the fittings through which fuel is withdrawn from a fuel tank must be located above the normal level of fuel in the tank when the tank is full.
Here at Titan Fuel Tanks, we have made every effort to make sure our tanks comply with the appropriate regulations. Our gravity-feed systems only supply diesel fuel through the fill neck hose. In other words, our systems deliver diesel fuel into the existing diesel fuel tank maintaining normal vehicle operations and safety requirements.
Note: The only gravity-feed fuel systems we provide are for Diesel fuel tanks.