Fill 'er Up! Fuel tank for a M101 CDN?

[greentruck]

I'm knee deep in a home-brew subtank design and install thread over in the 80 Forum. In discussing various tank options there, an idea hit me when I saw this tank:
http://www.tanksinc.com/index.cfm/p...tegory_id=148/home_id=143/mode=prod/prd83.htm

There's also an essentially identical-sized steel version:
http://www.tanksinc.com/index.cfm/p...tegory_id=133/home_id=59/mode=prod/prd121.htm

This got me to thinking I could get even more range when I need it most by adding a tank to the trailer, which will almost always be along with me when long range fuel is needed, at least to a base camp for further exploring.

Anyway, there's room under the M101 CDN in front of the axle. Would likely be a good idea to skip-plate it, but you still have good clearance as it bottom would still be well above the axle low point. Keeping as close to the axle as possible will keep tongue weight issues under control. Set it up with an in-tank pump and it should be easy to draw from.

The fill neck would need to be figured out and protected. It could just project into the bed, although I think a side fill of some sort might be preferable.

I want to keep cans of extra fuel out of the bed of the trailer because it takes up too much space. That's why I was looking into adding a subtank to the 80. Adding a tank to the trailer would really let the rig stretch its legs.

Anyone do something like this?

 

[Dell]

I'd rather run independent fuel cans...

that way... if the trailer is left behind at base camp...
I could still carry the extra fuel on board muh rig.

your option has limitations IMO

 

[Rubiconcruiser]

Those tanks are nice but you may want to check DOT codes in your area reference the usability of this type of tank mounted. There are a lot of states that frown on this, Just saying. Be safe if you use it,.

 

[greentruck]

Dell,
I can understand the attraction of cans, got plenty. I'm looking to get the cans out of the bed. It's also a matter of how we'll be using the extra range. If I get to someplace to base camp and I can't make it back to base on the 25 gallons in the 80, plus maybe another 20 to 25 in a subtank there, then I probably don't need to go. Since the subtank on the 80 will displace the spare, there's be a rear tire carrier and likely a spot for another one or two cans. So the tank on the trailer is not going to be an issue in terms of flexibility.

RC,
I haven't gotten far enough along with this project to look specifically into the regs that might apply in my local jurisdiction. I presume so long as its well mounted, has a solid filler mount, is top draw (NO gravity feed), and not inclined to leak and otherwise be up to commonly accepted practices, I should be good. Having been in the trucking biz, I know there are millions of reefer trailers running our highways right now with fuel tanks, so this should be no big deal. If you are aware of something specific that might apply, I'm interested in hearing more, but doubt there is anything special about doing this. Everything will be rated for its appropriate use and done right in terms of assembly.

 

[Rubiconcruiser]

A friend of mine has constructed his fuel tank 25 gallon on the underside rear of the axle, plated his Fuel Cell and actually piped the systen to a QD fitting on the rear bumper. He had it inspected as a precaution by the CHP and was given a green light to operate it but not for hire, if this means anything. Good luck with it,

 

[greentruck]

A friend of mine has constructed his fuel tank 25 gallon on the underside rear of the axle, plated his Fuel Cell and actually piped the systen to a QD fitting on the rear bumper. He had it inspected as a precaution by the CHP and was given a green light to operate it but not for hire, if this means anything. Good luck with it,

Yeah, glad it worked for him in California. I was thinking that might be where you had in mind. Back East, most states have no requirement for regular safety inspections of any type. If you do something stupid and its equipment-related, yeah, they'd hang you out to dry, but short of that not much to worry about...

Especially with a commonsense and by-the-book install with appropriate parts, should not be an issue here.

However, you do raise an important point to consider and look into. No fun to go to all the trouble and have some guy with a star tell you it's only cosmetic or worse, to remove it.

How did you buddy handle venting the tank? That's the thing I could imagine being an issues in Cali. I mainly want to deal with it for practical reasons, because I go to Colorado and the elevation change there requires some way of venting short of seeing just how big the tank will swell. I'm thinking it'll need a line up to a high point on the trailer bed, with check valve and vent cap. I think that'll get it vertical enough so that even on a sidehill it won't start leaking out -- at least anything I plan to drive on with the trailer attached

Other than that, it's a pretty straightforward exercise, with enough time + $$ of course.

 

[ntsqd]

The way that I handled the fuel tank vent on my 'glass bodied dune buggy was to run a tube up as high as I could get it while staying under the body, and then 180° down to a suitable spot where I had a short piece of fuel hose on the end of the tube. Stuck into the hose was a plastic body fuel filter, which was there only to keep out the dust. Can see into the plastic bodies well enough to know when it might need replacing. This was in KA and other than a couple idiots spotting the filter hanging by only one connection and telling me, while idling at a stop-light, that my fuel filter was disconnected (!) I never had any trouble - legal or otherwise - with it.

Two friends have had fuel tanks in a trailer. One built it from a Datsun bed, the other was an option on a Toy Box type trailer. Neither ever had any legal issues with them.

 

[greentruck]

ntsqd,
Thanks for the insight on your experience. Makes a lot of sense to me, run basically a J-pipe up and back down, instead of just going up and terminating. That way if anything did get spewed, it would drip down by the road, instead of all over the trailer. The filter termination is good, too.

I'm undecided on the check valve now, because that could inhibit the tank from equalizing. Maybe of I can find a "loose" one that inhibits rather that totally stops fumage getting past? So I still got some thinking to do on this.

I've eyeballed things and it does look like there's enough vertical distance to near top of the tub railing so that it would take holding a very extreme angle to actually get any sustained flow into the vent line, rather than just fumes and splash. Of course, I drive in Colorado sometimes, so...

 

[Mark Harley]

I say do it! The military had several built under tanks on M101A1 trailers that carried generators.
If it is tucked up into the frame and has skid plates to resist puncture it will be fine. A vent to elevation change and expansion from tempature is a must.

 

[ntsqd]

The rule in desert racing is that the tank (fuel cell actually) vent must have a section that is above the cell at any given roll-over angle. The vent hose forms a complete 360 that is beyond the dimensions of the tank/cell itself. Might be worth considering if you think that the trailer may go over.

Fuel cells do have a check valve in their vents. The one on the new cell in the 7S truck that I chase is so restrictive that our first race with it was lost due to the incredibly long re-fuel times. The old cell would take 11 gallons in well under a minute. The new cell took nearly 15 minutes to get 20 gallons in it. All because of the vent's check valve performing poorly. The mfg of this cell certainly heard from the truck's owner.

Because of this I'm not convinced that a check valve is all that necessary in a non-competition vehicle. Street cars and truck ran for years w/o them. The vent check valve in a late model is more for emissions control than for any real or perceived safety value.

 

[greentruck]

Interesting story on the Curse of the Check Valve
Yeah, I'll bet someone heard about that loud and clear.

Points out an advantage I could incorporate. The only time I need to worry about a check valve restriction is when transferring fuel. So I can put a regular valve, instead of a check valve, and just crack it open as needed. It could be a good way to adjust venting on the high altitude trails. Hmm, have to think on this more....

Thanks for the insight.

 

[ntsqd]

I don't think that I'd bother with any sort of valve in the vent line. Unless you're incredibly anal it will get forgotten and Mr. Murphy being who he is, it will be forgotten in the closed position.

 

[greentruck]

I was actually thinking of a valve that could be modulated and left cracked open most of the time, with the option of opening further under hot and/or high altitude conditions or for a complete shutdown if the trailer rolls. The whistling tells you whether it needs more venting or not, at least going by how my FJ55 acted.

You might be right, though, just let her vent is the simplest solution.

 

[greentruck]

Did a little more thinking about how this will work. Some details to be settled on several things, but I'm still trying to pin down what to use for the refueling hose.

First, you need to ground the truck and trailer together. Most of the time, simply having them hooked up should suffice, given that they both connected via the hitch (I know, iffy, but it's there) and the trailer wiring (pretty sure existing wiring is grounded to trailer chassis, but will check to confirm).

If not hitched, then a little trickier. When planes are fueled, they is usually a ground wire that ties them together. At the service station, the filler hose nozzle is made to ground against the fill neck and is tied to the station grounding system via mettalic sheathing in the hose IIRC.

As noted before, plan is to utilize an in-tank pump. I can wire it so it'll plug into power in the truck. But how do I dispense the fuel from one tank into the fill neck of the other?

There are a bunch of different 12 volt transfer tank pumps like you see in the back of every pickup that's near a farm these days. They look like small service station pumps. But that's overkill for what I'm doing, takes up space, and I'd guess needs a fairly large pick-up tube, unlike the small 1/4" line or whatever typically comes out of a fuel tank.

I could see a suitable rubber hose with just a brass tubing neck on the far end to hook into the fill neck of the tank. If there was a ground or ground wire between truck and trailer, that should deal with the potential for static -- I think -- and easy to hook-up with the in-tank pumps typically found in fuel tanks. Maybe I need to ground the trailer to earth also, just to have all my bases covered? Sounds simple, but since I'm dealing with gasoline, I want to get more than just my own opinion.

 

[Rubiconcruiser]

You are really gettin in to this stuff, and way too complicated I must say, safe for sure but probably overkill. Look into NAPA and their in line fuel pumps,I use one of these to pump from my Jerry can to the truck, works pretty well, safe and clean, no ugly parts hanging out. The other option would be a Y connector in the fuel filler hose in the truck, Valved off when not using it of course running from the tank to the valve. this is a more efficient way of doing this as gravity works in your favor, pump is a backup at this point. The vacuum in the fuel tank will siphon the fuel. Not very efficient though, altitude etc. In line pump looks best.

 

[ntsqd]

Modern car fill necks are set at a specific angle (I've seen it refered to as the "Beta Angle"). I'm not sure what that angle is, but not having it (like with an older car) makes filling the tank a pain with some cars. Was it me, I'd buy the part that surrounds a Heep YJ's (rectangular) or TJ's (round) fill neck (available in either black, chrome, or SST from places like here) and mount it to the body or frame with it's mount flange vertical as it is intended to be on the Heep body.

I would not count on the trailer ball connection for a good ground. This is a common assumption that frequently results in poor or no trailer lights. Any lubricant or rust there will have a large impact on the grounding effectiveness. Make sure that the trailer light connector has a functioning ground wire. I prefer to carry a ground wire to each light in addition to grounding to the trailer frame.
So long as the filler neck and the fuel tank are both mounted metal to metal they *should* have a ground path to the trailer frame, but it never hurts to ground them with a star washer under one of their mounting screws/bolts and grounding wires if needed.

I have, and have no idea where to get more, a couple QD's similar to an air hose coupler, but specifically for fuel. Outboard engines also have such things, but most are proprietary and I don't know that you can buy both sides economically and in a usable form. Might check mcmaster.com as they may carry something.
Fuel hose comes in 25 foot long spools. Could simply carry a long enough fuel hose and coil it up in a tongue box if you're going to have one. I'd plug the end with something just to keep dirt & insects out. One issue that you may run into is that most electric fuel pumps need to push against a restriction and you won't really have any. Long term this will probably shorten the life of the pump. It will depend on how frequently you use the system.

Was it me, and because I have a couple of them floating around loose, I would plumb one of these between the pump and the hose to the truck. It would add some restriction and filter the fuel so that you're not pumping carp from the trailer's tank into the truck's fuel tank.

I have a thought about how to do a quasi-QD using Instant Fittings. You could mount a bulkhead Instant Fitting somewhere on the trailer and use an Instant Fitting plug while driving. When you want to re-fuel from the trailer you remove the plug and insert a short piece of tube with the coil of hose clamped on the end of it. I would say to just use the Instant Fitting tubing, and you could, but it's not as flexible as fuel hose and would be more bothersome to handle.

 

[greentruck]

You are really gettin in to this stuff, and way too complicated I must say, safe for sure but probably overkill...
SNIP

RC,
Hey, you were worried about safety?

Static discharge is a potential problem any time you move gallons of gas between platforms that are electrically isolated from earth, which anything on rubber tires usually is. Last thing I want is to start a fire 200 miles from nowhere and burn down the 80 and trailer both. I think I've about got that figured out now though.

ntsqd,
Good point on going with standard fittings/angles/etc for the filler. I was considering an in-bed fill, but that will be a PITA to refuel.. Unless I can run a neck up between the arms of the drawbar, cutting something into the tub is probably the best solution.

Wasn't going to count on the hitch for ground, mentioned it more in terms of things already in place to deal with static discharge. Through the chassis grounds is another way to deal with it. I think I actually did run grounds to all the lamps when I rewired it (CRS kicking up again ), but I was thinking more about whether I should add a third means of grounding between the truck and trailer just for refueling? Probably overkill if the trailer wiring is grounded well and connected to the truck's wiring. The 80 has plenty of grounding on its end, so long as things are hooked up.

The filter is a good idea and will deal with any need for restriction. I'm leaning toward in-tank pump to keep things on the trailer packaged as neatly and cleanly as possible.

I'm also leaning toward a quick-disconnect for the hose, if I can find one rated for moving gasoline. If specifics on what were used come to mind, I'd appreciate a lead, although marine parts may very well be the solution as you pointed out.

 

[ntsqd]

I wasn't thinking so much of cutting the bed and inserting one of those mount flanges into it, more just that using one of those flanges got you an angle that will work with modern fill-hose nozzles & not be a PITA.

If you have a consistent & reliable ground path between the truck and trailer now I would not add anything to it. Doing so will create a ground loop and who knows what kind of weirdness that might bring on.

I'll try to see if I can find any marking on those QD's that I have to search for. Air hose stuff is likely not a rubber that will play well with fuel.

 

[Rubiconcruiser]

Ill check on Friday with a hose supply company and see if I can get you a QD part number. Hang loose on this idea for a day. Jim

 

[greentruck]

Jim,
No problem. This is likely an early spring project, once the garage gets reasonable. Heck, with winter the way it's been lately, that could be Feb. 2...

I can of course, like the parts squirrel I am, start stashing away parts as I come across them in the wild...