To the best of my knowledge, a fuel tank (unless it is a DOT approved fuel CELL) cannot be mounted in the bed of a vehicle. It has to sit between the framerails secured to something other than the bumper (i.e. crossmember, etc.)

I would not vent the tank into the cap in any way, shape, or form. It's just not a good idea. Venting outside is the only way to go.

To sum it up...remember the Pinto? You don't need to replay that scenario...

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I see a ton of those construction pickups running around here all the time with those big tanks in the bed of thier pickups . For re-filling loaders and Cats on site . You think those are DOT approved ? Just wondering , those are cheap to come by used . They must be legal because they`ve been using those types of tank for decades .

Jeff /wwwthreads_images/icons/cool.gif

 

What about all the thousands of transfer tanks that ride around in the bed of trucks? Are they all DOT approved? I doubt it (I know the one we use on our farm has no DOT sticker on it).

Yeah, I know venting outside the cap is the way to go. What I'm wondering is, if I have an outside vent, and a good cap on the tank, need I worry about vapors still somehow building up inside the cap? I could just leave a window cracked a bit to solve this problem, I guess...

Securely mounting the tank isn't a problem.

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99% of those are diesel fuel. Flammable, but not explosive like gasoline.

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OK, that's a red herring...I'm looking for answers to the above questions. I'm not worried about DOT certification. Anyhow, any tank I would buy that was formerly installed on a heavy-truck would necessarily already be DOT certified. On to the real questions...

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OK, let me rephrase my previous statement:

It is MOST LIKELY ILLEGAL to have a tank of your description mounted in the bed of the truck. Yes, a fuel tank SHOULD be DOT certified. However, to the best of my knowlegde you have to have a specially approved fuel cell to do what you want to do. Whether or not you care about the laws, you should still be concerned for your safety. I recommend checking with the state to find out if what I say is true or not.





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OK, perhaps I'm not being clear. Please leave the mounting and related questions to me. I do, however, have some questions I am seeking the advice of others on. Please limit responses to those areas, and other potential areas I have not considered. Thanks. Those questions are:
1. If the truck has a cap on it, and I vent the tank to outside the cap, does anyone see a problem with vapor buildup inside the cap?
2. My thought is to use the aux. tank as a fill-up tank for the std. tank. By that, I mean I’m considering just running a line from the aux tank to the main tank and using it to fill the main tank, instead of duplicating all the fuel lines and using the aux tank separately. Any problems with that thought?
2a. How do I plumb the line from the aux. tank into the main tank reservoir?
2b. If the aux tank is in the bed, above the main tank, can I just run a valve on the aux tank to close it, and open it and let it gravity fill the main tank? Or should I run a small electric fuel pump to transfer the fuel? What would work good for a valve and/or pump? I’d like to use electrically controlled ones so I can ‘refuel myself on the go.’
3. What am I not thinking of? I know the tank will need to be grounded…and I know I’ll need to figure out a way to fill the tank easily if I put it under a cap. The cap isn’t on all the time, but generally, when doing a road trip, I do use it so I have some more storage space. Is there a better suggestion or solution to the problem that I haven’t considered? (I know I could use gas cans or jerry cans…)
4. Is the refueling on the go thing too much of a hassle? Should I just build a system that uses a standard transfer tank and just pull over and refuel myself in the standard fashion?


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Is there an aftermarket (or factory) larger tank for your truck that will work? I'd assume that by the time you spend $$$ for a second tank and related plumbing, you could drop a larger tank and be done.

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/wwwthreads_images/icons/crazy.gif Alllllll RIGHT!....stop it! I'm tired of this legal-beagle paranoia!/wwwthreads_images/icons/mad.gif If Farmjeep wants to carry a garbage can bag of gasoline in his pickup, It's HIS lookout!/wwwthreads_images/icons/frown.gif All FJ is looking for is the MECHANICS of connecting the "fuel pod" to the existing fuel system of his pickup, and I'm about to give him some direction as just how to DO that!/wwwthreads_images/icons/tongue.gif Here is what you do: (1) get a fuel tank off a truck that is the size and shape that you want. (2) vent the tank to atmosphere.....through an in-line fuel filter preferrably......any filter as used on an automobile. (3) install an electric changeover valve (NAPA three-port is just fine; ferget them six port suckers) in the line between the existing fuel tank and the engine. Connect the port that is open-on-energize to the new fuel pod. (4) install switch on dash, CONNECT TO IGN CIRCUIT. (5) Install fuel gauge for new fuel pod IF DESIRED. That's it! That's all you DO!/wwwthreads_images/icons/tongue.gif No disclaimers, no legal bulls#it!/wwwthreads_images/icons/frown.gif So.....how does this work in practice? Here's how: You burn up your fuel that is in the main tank. When the main tank is down to 10 or 15% you flip the switch. The fuel will flow from the new pod to the engine and A PORTION OF IT WILL BE RETURNED TO THE MAIN TANK via the fuel return line./wwwthreads_images/icons/crazy.gif So, you refuel AND run at the same time. You keep a wary eye on the main fuel gauge and switch back when the main tank is full again./wwwthreads_images/icons/crazy.gif That's it!/wwwthreads_images/icons/crazy.gif

CJDave
A moonguy-operated Jeep Skunkworks in the "Heartland" building the Ultimate SNOJEEP.

 

Thanks Dave,
I'm assuming that I will need to run a electric pump on the fuel tank to feed the engine, right? Here's the quandry. Looking at the truck (fuel injected) it appears as though the in-tank fuel pump gets the fuel up to pressure and there is no secondary pump that boosts pressure...only a pressure regulator (right before the engine). So I need to run a electric pump that puts out sufficient pressure to feed the engine by itself, right? Do I need to install a relay to shut off power to the main tank fuel pump when I'm running off the aux. tank? Would it be possible to run a T on the return line and have the aux. tank pump directly into the return line instead of into the feed line, thereby bypassing the need to tap the hi-pressure feed line?

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/wwwthreads_images/icons/tongue.gif Yes, you could do that. Fill the main tank via the return line with a pump. If I were you, I would connect the vents as well. One little problem......the fuel pod could siphon into the main tank through the pump, so a fuel restrictor needs to be installed. I could be wrong about this, but I THINK that the three-port filters as used on the CJ have a third-port restrictor that takes pressure to open. If so, you could use a filter like that in the feed line between the extra electric pump and the main tank return line. I had a 2000 Series IH with the RD 460 Gas engine and it had an electric pump in each tank with a shuttle valve which shifted by flow, so as the pump in a tank started, the fuel pushed the valve shutttle over and the engine port was connected to that valve. It was neat, the fuel was switched by switching pumps, and it gave me two different pumps for reliability. If one pump crapped out we could open the crossover hose and the fuel from that tank could go across to the tank with the still-functional pump./wwwthreads_images/icons/crazy.gif

CJDave
A moonguy-operated Jeep Skunkworks in the "Heartland" building the Ultimate SNOJEEP.

 

An additional suggestion for the vent. I'd look into using a marine through hull fuel tank vent for your cap installation. It has a barbed hose inlet and should help when using the cap. It stays mounted to the cap and they make a small stainlesss or glass cover which will hide and protect the vent. The vent has a stainless mesh screen inside, which is not good for your application, continue to use Dave's in-line fuel filter in your application. Mount it on the side of your cap with the opening pointed down and back.

PEACE !! /wwwthreads_images/icons/smile.gif
w

 

One last question...anyone have a suggestion on what sort of disconnect fittings to use on the fuel lines so the tank can be removed if need be?

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Hydraulic couplings as used on snowplows would be my first thought. About the correct size, can be firmly mounted, seals can survive the petrochemical fluid (Although the reformulated gas hardens some Coast Guard approved fuel lines-random thought) and they have dirt protectors available when they're not in use. /wwwthreads_images/icons/smile.gif

Whatever you decide I'd only trust a real valve as a true gasoline shut-off and it would be something I could wire closed or open.

PEACE !! /wwwthreads_images/icons/smile.gif
w

 

Farm Jeep what kind of truck are we talking about?I had a thought that might help you out a little If we are talking GMC or Chevy you could get a gas tank from a Suburban which mounts at the rear between the frame rails. Some of these were 39 gallon tanks.This would be out of the bed and should be an easy conversion.Some thing simular could be done with either a Ford or a Mopar using either a Bronco or a Ram Charger.Although this would be more of a perment tank than you mentioned that you wanted it would be out of the way and allow full use of your pick up bed.

Take care of the pennies and the dollars will take care of themselves.

 

My first thought was to tee into the fuel return line to pump from the aux. tank to the main tank but this might create a siphon effect and require a shut off valve. The vent could tap in here or at the main tank vent and the aux. tank wouldn't need a separate vent.

I've thought about this to transfer fuel from a couple cans mounted to the spare tire carrier, but if it's not DOT approved, I guess I better not./wwwthreads_images/icons/smile.gif

I've replaced so many parts that my old Jeep has become my new Jeep.

 

Short bed supercab 99 F-250 v-10 4x4 Ford...

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Eww, he said the 'F' word! /wwwthreads_images/icons/wink.gif

I'm sure you could find a rear tank from a dual-tank Ford in the Junkyard. Wether or not these would work on your new truck... I dunno, I'm just giving you options here. The dual-tank trucks also had spare tires under the bed so it may not even take place of the spare.

You could get a plastic fuel cell intended for a boat. They come in lots of sizes and are easy to strap down/up. Perhaps you can find a way to tap into your fuel-filler hose and have a gravity feed, for a bed-mounted tank, right into the fuel-filler hose to fill the main tank. If you mount the spare tank between the frame rails an electric fuel pump could pump the fuel over, and the main tank's pump could do the pressurizing.

'89 Comanche, '89 Wrangler, '74 Postal