Gravity-feed of diesel fuel: Is it legal?

[FTG-05]

Here's my opinion.

What is yours and why do you think and/or know that it's legal/illegal?



Gravity-feed: Is it Legal?

There is probably more confusion on this subject than any other in the discussion of aux fuel tanks for pickup trucks. What follows here is the relevant regulation from the Department of Transportation (DOT) Code of Federal Regulations (CFR). However, I am not a lawyer nor is any of this discussion to be construed as legal advice; it’s simply provided for your use as a basis for further investigation for your own information and use.

The relevant portions of the DOT CFR codes that apply to gravity feeding of fuel tanks are 49CFR393.65 Fuel Systems and 49CFR393.67 Liquid Fuel Tanks. The relevant portions of these sections are as shown below. For a complete copy of the entire texts, see the link for the DOT in the Appendix and then follow the link to the 393 section of 49CFR.

49CFR393.65, Fuel Systems: “(d) Gravity or siphon feed prohibited. A fuel system must not supply fuel by gravity or siphon feed directly to the carburetor or injector.” [Ed. Note: misspelled word corrected.]

Note that 393.65(d) title makes a declarative and complete sentence with an adjective, noun and verb i.e. “Gravity …. feed prohibited”. Quoted out of context, it is easy to see how people say that “DOT prohibits gravity feed”. However, this sentence is not a regulation, it’s a paragraph title and it is completely negated by the actual regulation that follows it i.e. “… must not supply fuel by gravity … feed directly to the carburetor or injector.” Since I am supplying fuel via gravity feed to the OEM fuel fill line and not directly to any carburetor or injector, I see no violation of 393.65.

49CFR393.67, Liquid Fuel Tank (partial): “c) Construction of 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 Except for diesel fuel tanks, the fittings through which fuel is withdrawn from a fuel tank must be located above the normal level of fuel in the tank when the tank is full.”

Since I am withdrawing diesel fuel and only diesel fuel from the bottom drain fitting of my aux fuel tank, I see no violation of 393.67 with my aux fuel tank functional design.

There are other regulations that apply to fuel tanks and systems at the Federal level, mainly Federal Motor Vehicle Safety Standards and environmental regulations. Vehicle safety standards for gravity feed mainly follow DOT as far as I’ve seen; if so, I see no violation there. Environmental regulations have to do primarily with leaking fuel.

There are a number of regulations that you need to be aware in installing your aux fuel tank; these are called out in 49CFR393.65, Fuel Systems. Examples include not having any fuel lines near flame or heat sources (i.e. the exhaust system); not having fuel lines outside the body of the vehicle or in the interior/passenger area of the vehicle. Anyone installing an aux fuel tank in their vehicle should review these regulations in their entirety to ensure their installation meets all DOT and Federal Safety requirements.

Basically, if you install the aux fuel tank using the same or similar workmanship and parts standards as the OEM design, you should have no problems with either safety standards or with leaking fuel. Note that any leaking fuel is a violation regardless of whether or not your fuel system is completely OEM or has been modified with the addition of an aux fuel tank.

The above is from this paper: http://www.rocketcityrockcrawlers.c...talling an Aux Fuel Tank paper 2007-06-18.pdf


Discuss.

 

[dpantazis]

with our trucks, i don't know if you can get enough fuel flow with gravity alone. you would have have a solenoid valve before the fuel pump to select your source

remember that the law was written not because of intelligent product standards, but as a result of loss of life and property.

it does not matters what educated vehicle owners and the law says.. its going to be more of a headache if/when someone with some sort of a enforcement capacity misunderstands the requirements and feels compelled to do something.

 

[stroker21]

My grand dad was doing some hauling and installed a tank on his pickup. He went to DOT to have it inspected to make sure everything was ok. He had a gravity feed system with a valve in place above an inline filter, if for nothing else to shut the fuel off to change the inline filter. They approved of his system. They said it was because of the valve being in place that it was approved. Later he got tired of it taking so long to fill up his other tank that he installed a small pump from the zone($50) down line from the valve and they still approved it. I think you are going to want a valve in place for stopping the fuel anyway in case of inline filter change or having to change a fuel hose years later. The valve will make it legal and it cost maybe $5.

 

[bushpilot]

I wouldnt put one <and im pretty close> in my truck WITH OUT a
valve @ the tank outlet...and i wont install one unless its SAFELY
bolted in.

if you ever wanna remove the thing youll wish you had a valve
at the outlet !

Consider this, regarding the legality of the gravity feed tanks...theyre
made of steel or alum. and your FACTORY tank is PLASTIC...which
do you think has a better chance of getting punched or cut ?

then consider where the alum. tanks on a big rig are placed...do they
have shut off valves ?

 

[kenholl]

I think you are going to want a valve in place for stopping the fuel anyway in case of inline filter change or having to change a fuel hose years later. The valve will make it legal and it cost maybe $5.

Big-rigs have gravity feed crossover line between tanks, keeping the fuel weight balanced. I used to own a Peterbilt, and ran over something in the highway, rupturing my secondary (non-draw) tank. I had no choice but to watch the fuel run onto the ground from the breech. However, I suddenly realized that there was no shut-off valve between the tanks, and I was carrying about 250gals. of fuel. I was not willing to watch both tanks drain onto the ground, so climbed under the truck into all that nasty smelling fuel and disconnected the crossover line from the damaged tank, and lifted it up to the frame to let gravity do the rest. I could smell diesel in my skin for days after that!

I figure I lost about 150gals. of fuel that day. A simple shut-off valve would have saved me about 25 more gallons, and reduced the number of noses that raised when I walked past.

 

[pdt1081]

Our dump trucks at work have shutoff valves on the tanks.

 

[bushpilot]

Our dump trucks at work have shutoff valves on the tanks.

thats good...a worthy precaution !

 

[FTG-05]

I'm surprised: where are all the "gravity-feed is illegal" types? Perhaps they're all over at T*D*S?

 

[bbressler]

My vote is it is legal...(cause that's how mines' installed).

I do have a shutoff at the tank.

 

[Flopster843]

I have the smooth finish version of THIS TANK coated with THIS STUFF bolted in my short bed. It's plumbed with THIS KIT which includes a ball valve and goes into THIS FILTER before going to the float valve in the filler neck. It takes a couple hours to fill the main tank from 1/4 to full since it is only flowing through a 5/16 fuel line. On long trips I turn the valve on before I leave and let it gravity feed the entire time I'm driving and it is way more than my truck consumes, so the main tank is always full until the aux runs out. It will gravity feed all of the fuel except for about the last 1 to 1 1/2 inches in the tank. I've never had anybody say anything about my setup. I've even had the DOT look at it at a couple scales and everything was .

BTW: The tank doesn't interfere with my goose neck ball in any way.