http://www.northerntool.com/images/product/images/3490014_lg.gif
RDS Auxiliary Fuel Tank/Toolbox Combo — 51 Gallon, Model# 72646 From Northern Tool



Has anyone Installed this tank in a 2008 6'6' bed. If so how did you route the fuel line?

I have a 5th Wheel Hitch in the Bed was there any problem with the hitch being in there?

Thanks for your input

I've got an older model of that tank. Mine's 60 gal I think though. Anyway, I didn't have any problem getting it to fit in front of my wheel wells. I also have a gooseneck ball, that doesn't seem to be a problem either. I have never used a fifth wheel hitch, but if it doesn't come up past your wheel wells you're fine. Those tanks (if it's as similar to mine as I think it is) sit below the top of the bed. They aren't like the toolboxes so with a travel trailer, you shouldn't have a problem.

As for routing it, I got a fuel pump which I mounted behind the tank against the front of the bed. I got some rubber fuel hose and ran that down to the side of the tank and drilled a hole in the bed toward my filler cap just big enough to fit the hose. There should be a vent hose coming from your fuel filler hose (the big one). I just "t"d off of the vent hose and hooked the incoming aux. tank line to it. Then ran electric to a spot under my dash so that the tank doesn't run without the key on, and put in a switch from an auto parts store to turn the pump on and off while the truck's running.

Have a look at pics in my garage. Not exactly the same setup, but same principle. I stuck a 45 gallon `pancake' RDS tank on my unit and use the gravity feed system they sell. The line is just a 1/2" hole through the box and I added a low pressure in line fuel filter between the two tanks for added safety (not required). This tanks fits no problem along with my Reese 16k slider hitch (4" to spare). I dont' have an update pic with the Retrax bed cover, but I take my topper off during camping season and place the cover on top (it just fits with no room to spare). This provides security when not hook up to trailer (don't want the hitch to be stolen!:eek:).
Hope this info. helps you - you should be fine with your tank and hitch.:D

Thanks
So I would HAVE to buy a Fuel Pump and drill a hole in the bed of my truck. Those are both doable.

mpuppy you stated gravity feed system? That sounds better then putting in a fuel pump and running electric. Can you explain a little about it? Also I am going to do a search on where to get a tank like yours. I don't really need or want a tool box.

What about doing an OEM replacement like one from Titan tanks or Aero tanks. There are a few that make the direct replacement setups that range from 50 - 60 gallons and don't affect bed space at all.

DuraLee, look on Northern Tools site and you will find a install kit that has all the parts and lines in it. It installs right into the fill neck and has fittings so the fill spout will not overflow. I think it is $70 bucks and will save a lot of trips to the hardware store.

What about doing an OEM replacement like one from Titan tanks or Aero tanks. There are a few that make the direct replacement setups that range from 50 - 60 gallons and don't affect bed space at all.

If you're not wanting a toolbox, these tanks are great options. I kind of wish I went this direction, but now that I have the toolbox in the bed, my truck is nice and clean inside so it's 6 and 1/2 dozen either way.

I ordered this one along with the install kit... Any one got any advice or tips about the install?

http://www.northerntool.com/images/product/images/3490044_lg.gif
RDS Auxiliary Fuel Tank — 37-Gallon Capacity, Model# 71804

THE OEM ones are way to expensive

I ordered this one along with the install kit... Any one got any advice or tips about the install?

http://www.northerntool.com/images/product/images/3490044_lg.gif
RDS Auxiliary Fuel Tank — 37-Gallon Capacity, Model# 71804

THE OEM ones are way to expensive

I put some super, super thick "electrical tape" under the tank on the top of the bed ridges so that it didn't rub holes (in either the tank or the bed) or rattle. You could do something similar maybe with a small layer of silicone or something.

hbcbob... Great Tip...... Thanks

I had that tank in my 6'6" bed with a fifth wheel slider hitch and it worked fine. Used the gravity feed kit northern sells and it has worked great. When I traded trucks I went with the 8' bed but moved the tank and kit to the new truck. Just used a piece of 2" pipe and 2 hose clamps to splice the filler hose back together. Mine is the 60 gal tank but I usually only put 50 gals in for expansion. Great tank as I had a Undercover bed cap on the short bed and it closed over the tank. Kept the cover on for work then removed it when towing the camper. Only problem is with the fuel gauge. When the truck has run awhile the computer sees the gauge not moving and thinks it is broken. Gauge will drop to E. Just watch your fuel used and you can keep track. When it gets into the main truck tank gauge will work right.

I guess I am not sure how the gravity part works?

If I start with both tanks full as I am going down the road the tank in the BED keep a steady flow of fuel into the factory tank and keeps it full?

At some point the fuel gauge will screw up and drop to Empty. (But the tank in the Bed will keep flowing until EMPTY. After the tank in the Bed gets Empty and the fuel in the factory tank starts going down the fuel gauge will work again? Is this right?

On another question. Those of you who have the tank installed in the bed at what point (where) do you attach the gravity fed hose to the overfill on the truck?

I have a an RDS tank in my bed with a gravity feed system. There is a threaded tap at the bottom of the tank on the side. I ran a rubber hose from there through a valve, through the bottom of the bed, and spliced into the fill line near the factory gas cap. As long as the factory gas cap is on good, I can just leave the valve open and the bed tank fills the factory tank as fuel is used. My fuel gauge in the cab reads empty most of the time if the bed tank is has fuel in it, but once the bed tank is empty the fuel gauge funtions properly. The best part is I can usually go 1500 miles between fill-ups.

Thanks Wes R. I am pretty sure thing will become clear once I get my grubby hands on everything. I need pictures if anyone has any. Pictures say a 1000 words.

Thanks for all your inputs

Thanks
So I would HAVE to buy a Fuel Pump and drill a hole in the bed of my truck. Those are both doable.

mpuppy you stated gravity feed system? That sounds better then putting in a fuel pump and running electric. Can you explain a little about it? Also I am going to do a search on where to get a tank like yours. I don't really need or want a tool box.


The toolbox is not that big, about 5 or 6 inches tall and is very convenient. See my garage for pictures. it a great system and if you get one get the install kit, its great and easy to install. Mine is the 60 gal and has a gauge. Can't beat it for the money. Just google them for a dealer near you.

I have a similar tank, but went with the 45 gallon unit from RDS along with the RDS gravity feed kit. The kit comes with most items required (I added an in line low pressure fuel filter and also an air filter for the vent tube). There is a ball valve when you want to transfer fuel from the aux. tank to main tank. There is a float valve in the kit that prevents overflowing the main tank.:eek:

So far I love this set up and have had no problems. I have read on the forum not to leave the valve open all the time as you will get some kind of idiot dash light error. I just turn it on when I need to re-fill. Now we can hook up and drive for +700 miles before needing to re-fill.:D

Just a thought but 50 gallons of fuel will add another 365#'s of weight to the GVW. I don't know how heavy your pin is on the fifth wheel.


I am going through the whole "I wish I had bought a dually" remorse right now..

Well for one thing I am only getting a 37 gallon tank and I am fine as far as pin weight goes. (I hope) I have my weights but I don't know how to figure out what my pin weight is.

Just my truck empty (but full of fuel) is 4040 front axle and 2700 rear axle. Total of 6740

With the 5er hooked up and with wife, daughter in I am 4240 front axle 4640 rear axle 7020 trailer... Total of 15,900

The pin weight on my 5'ver is about 1600lbs and total trailer dry is about 8900lb. This is very similar to the cougar and you are definitely fine even with a 50 gal tank. +400lbs is not even going to make a difference at these levels.:)

Whew........ I am glad you posted that answer.....

I built mine out of steel welded a filler cap on it with a vent line, the tank drains gravity into the main tank the vent line and the filler line are plumbed into the vent line on the main tank . I got the tank sprayed at line-x . IT gives me an extra 37 gallons. worth the effort and save on fill ups.

I wasn't trying to sound like a weight nazi guy's, just bringing up something that needs to be watched.
I bought a '08/3500/CC/LB/D/A/SRW/4x4 so I wouldn't be limited when I found the right 5th wheel, but I was wrong. GM lists my curb weight at 6380# (liars) but when I drove it over the scale it weighed 7450# full of fuel, no passengers.

7450# truck and fuel, actual
650# Family of 5, rough est.
200# stuff in truck (not trailer)
200# Hitch, rough est.
-----------
8500# truck/stuff

9900# GM's listed GVWR
8500# truck/family/stuff
---------------
1400# left for pin weight/cargo capacity:mad:

So if I play by the rules, my 1ton Duramax can only pull a 7K trailer. Pin is usually estimated 20% of the trailer weight.I'm not sayin' that the truck won't pull anything I buy just fine, it just pisses me off that GM screwed us on our actual weights, limiting me on what 5'er I buy. I want to try and stay as legal as I can.

Long story short, I cannot add an aux/larger fuel tank on my truck like I had planned.

Sorry for the long post :o:, move along folks, nothing to see here.

Here are some pictures of mine with a "gravity feed" system.

View of the bed:
http://i99.photobucket.com/albums/l305/kwreeves/Picture105.jpg

Zoomed in on the left (driver's) side of the tank:
http://i99.photobucket.com/albums/l305/kwreeves/Picture106.jpg

The valve and rubber hose running through the bed. The clear plastic hose is a vent line from the top of the tank. This is all in the gap between the side of the bed and the left side of the tank.
http://i99.photobucket.com/albums/l305/kwreeves/Picture107.jpg

This is a view taken from above the left rear tire towards the back of the cab. The large rubber hose is the OE filler hose running from the gas cap to the OE fuel tank. The smaller rubber hose that "T"s into it is the hose coming from the fuel tank in the bed. The small open ended hose is the clear plastic vent line for the fuel tank in the bed.
http://i99.photobucket.com/albums/l305/kwreeves/Picture108.jpg

It's not the cleanest install, but it was my first one and I was in a hurry while doing it. I've been pleased with it so far. However, if you're going to leave the valve open from the bed fuel tank to the OE fuel tank, make sure your OE filler cap is on good or else your in bed tank will drain out the OE filler cap.

Looks great. Does the vent line spill any fuel whan the tank sloshes around? I was thinking of tying my vent line to the small line at the filler.

It spills a very small amount. At first I didn't have the plastic hose on it and I just let it vent to the top of the tank. If the fuel sloshed around a lot there would be a tiny puddle on top of the tank, probably a 1/4 of an ounce at most, but you could smell the diesel walking by it and the diesel residue accumulated dirt. The smell and the dirt is why I routed it under the bed.

Great Pictures Wes R. thanks a bunch...

agreed the in box gravity feed tank is the key to life. but i have a l shape tank that holds roughly 105l and a tool box on top of it so its un noticable. but its definatly worth the money to buy or make.

I think your numbers are off there Aaaahhyes68.
I just looked at the GM website to confirm. Max. 5'ver weight is 14,800lbs with a GCWR of 22,000lbs. This rating allows for 7200lbs for the truck weight.

Not sure if your truck is a 4x4 or not but a SRW 3500HD C/C weighs in at 6994lbs dry allowing a max payload to bring it to 9900lbs. Regardless, the GCVW is still 22,000lbs. Remember that your pin weight is added to the payload, but don't add it in again to find your GCVW.

For my case:
2500HD C/C 4x4 6670lbs
cargo (passengers, fuel, hitch, etc...) 1100lbs
pin weight 1450lbs
Total 9220lbs (no problem here)

Trailer weight itself 9000lbs (dry)
Cargo 1000lbs
Total 10,000lbs

GCWR of truck and trailer is 17,770lbs (6670+1100+9000+1000). If you add the pin weight on the truck total then then means you need to take it off of the total weight of trailer when doing your calculations. Technically I still have another 4000lbs to play with (though I wouldn't as that would be at the max. weight).

Anyway - sorry to be long winded, but wanted you to have the proper information.:cool:

mpuppy.... I do not care what the GM website lists what either of our trucks weigh. I have learned by fact the listed #'s are not correct for my truck, I cannot verify your truck. The scale does not lie.

My certified/actual weights are correct, for my truck.

7450# truck and fuel, actual
650# Family of 5, rough est.
200# stuff in truck (not trailer)
200# Hitch, rough est.
-----------
8500# truck/stuff

9900# GM's listed GVWR
8500# truck/family/stuff
---------------
1400# left for pin weight/cargo capacity for my 1 ton truck .


I no longer believe door/glovebox stickers. I do not believe trailer mfr. pin weight/UVW stickers. I wanted to believe them, but after having my truck and a few trailers pin's weighed (always being close to 30% over), I don't believe shat that is listed by any manufacturer.

I'm eager to learn and not trying to be argumentative. I am interested in actual weights, not mfr. listed weights.


Anywayz... my 1 ton truck doesn't have the capacity for another 30-40 gal's of fuel unless I wan't to haul a 5th wheel with less than a 1400# pin weight.


Cheers :beerchug:

Another trick with the gravity feed is to never open the truck filler cap while the aux tank valve is open. The air bubble that is formed at the filler neck helps with keeping the main tank from overflowing. Also if you always run the aux tank empty then fill it up with a fixed amount of fuel (I use 50 gal) then fill up the truck tank. Then you can use the fuel used display in the DIC to watch the usage. When the DIC says you have used the amount you put in the aux tank, you still have the truck main tank and a working gauge at that point.

Another trick with the gravity feed is to never open the truck filler cap while the aux tank valve is open. The air bubble that is formed at the filler neck helps with keeping the main tank from overflowing. Also if you always run the aux tank empty then fill it up with a fixed amount of fuel (I use 50 gal) then fill up the truck tank. Then you can use the fuel used display in the DIC to watch the usage. When the DIC says you have used the amount you put in the aux tank, you still have the truck main tank and a working gauge at that point.

If I run my vent from my aux. tank to the small line at the filler- will I lose the air bubble and have a problem?

Another trick with the gravity feed is to never open the truck filler cap while the aux tank valve is open. The air bubble that is formed at the filler neck helps with keeping the main tank from overflowing. Also if you always run the aux tank empty then fill it up with a fixed amount of fuel (I use 50 gal) then fill up the truck tank. Then you can use the fuel used display in the DIC to watch the usage. When the DIC says you have used the amount you put in the aux tank, you still have the truck main tank and a working gauge at that point.

Couple good tips. So in other words get in the habit of turning off the in-the-bed tank valve BEFORE opening the main tank cap..... Thanks....

I also learned this afternoon that if I have a Fuel Filter (under the bed) that filters the fuel coming out of the in-the-bed tank I will in a sense filter the fuel twice that comes out of the in-the-bed tank. So many pluses

If I run my vent from my aux. tank to the small line at the filler- will I lose the air bubble and have a problem?
That I don't know. Mine is just vented under the truck. It will leak a small amount if I park on a slope right after filling, maybe a few ounces.. I only had it leak around the filler neck once and that was after I had taken the fuel cap off.

I welded mine up myself and plumbed it into the vent tube with an in line filter. I have a ball valve on mine near the tank. If you leave the valve open it makes the gasket on top of the stock tank leak. Some guys trucks do and some dont.

Also ive heard that if your tank is always left that full (really over full since the aux dumps more in thank filling up normal) that the sending unit screws up after a while. In my opinion there is no reason for a fuel pump on the tank. I am happy with a ball valve. If you want to be tricky plumb in a valve with a solenoid on it and run a switch to the cab.

I found a 12volt seloinoid at WW Grainger, which I plan to use.

I have the same 37gal. tank in my bed, its mounted under my tool box (which i had to spacer a little bit), I painted it BBQ black, when it dried it matched my bedliner perfect. If i didn't already have the toolbox I would have bought a bigger one. The toolbox has a air tank/ compressor for the horn plus an airline running off of it so I can air up/down tires, or rear airbags. I'll try to take some pics and post them.

Wow I am getting so excited. But the darn tank will not get here until next week sometime you guys have giving me some great ideas...

I like the idea of the compressor and train HORNS OMG how much fun would those be..

You have no idea until you hit the switch one time at someone and see the reaction. check my garage for pics.

Alright so I put some pictires up in the garage of the aux. tank, air tank/compressor, air hose, and where i spacered the toolbox, they are crappy cell phone pics but you get the idea.

I ordered this one along with the install kit... Any one got any advice or tips about the install?

http://www.northerntool.com/images/product/images/3490044_lg.gif
RDS Auxiliary Fuel Tank — 37-Gallon Capacity, Model# 71804

THE OEM ones are way to expensive

Have this tank. Works great. Using the gravity kit. Pics in the garage.

Tank is Installed with a Fuel Filter and it is working GREAT........

Thanks to all of you... Now I am working on setting up a new Computer...(Old One Crashed)