393. 67 - Fuel Tank Mounting Requirements – Fuel Fill Pipe Violation

Currently 393.67-12 states :A liquid fuel tank manufactured on or after January 1, 1973, must be designed and constructed so that, (i) The tank cannot be filled, in a normal filling operation, with a quantity of fuel that exceeds 95 percent of the tank's liquid capacity; and (ii) When the tank is filled, normal expansion of the fuel will not cause fuel spillage. A company contacted CVSA to see if the modification to their Kenworth W900 fuel tank, due to a manufacturing error, would be enough to meet the requirement of 393.67-12. Their claim is the pipe inserted into the fuel tank would only allow the rated 100-gallon fuel tank to be filled to 87.19 gallons. (see attached letter) Further to that, two separate 2021 Kenworth tractors that had the fill pipes mounted in the vertical position and each tank had an anti-siphon device extending into the fuel tank were inspected. The device has slits in it (pictures of the anti-siphon device inside the fuel tank is attached) that would allow the fuel tank to be filled to 100% capacity. Kenworth later provided the company a letter stating that there is a 3” filler neck designed into the tank (see attached letter from Kenworth). This filler neck is not visible with the anti-siphon device installed. I have also previously stopped other tractors with their fill pipe again mounted in the vertical position, where I found vent holes drilled into the filler neck, allowing the fuel tank to be filled to 100% capacity (see attached photos).

Now that a manufacturer is purposely installing fuel tanks with the fill cap mounted in the vertical position, as there is no way to verify roadside that this fill neck is in place, or if there are any vent holes drilled within the fill neck, clear guidance needs to be provided to enforcement, manufacturers and installers on whether the fill pipe mounted in the vertical position is permissible, due to the potential of filling the tanks beyond the 95% allowed capacity.

: Option 1 - 393.67-12 needs to address where the fill neck is allowed be positioned on the tanks, such as off set to the side, to ensure there is no potential way to make a simple modification that would allow the tanks to be filled beyond their 95% capacity, so I am requesting a petition to NHTSA. Option 2 – with guidance from the manufacturer, can CVSA prepare guidance for Operational Policy 15 to ensure uniform interpretation of 393.67 in relation to filler pipes