Fuel transfer tank and pump questions

[JCasper]

I am thinking about buying one of these and have some questions.



L Shaped Auxiliary Transfer Fuel Tank — 95 Gallon, Smooth and Diamond, Model# 70388 | Fuel Transfer + Storage Tanks | Northern Tool + Equipment



First question is, how are they for quality?



Do those of you that carry extra fuel find it useful, or a hinderance due to the loss of bed space? I plan on a few road trips each year with my TT and would like more then the 300 mile range I have with the stock tank.



How do I plumb it in to fill into my stock tank? Can you gravity feed it somehow, or do you need a pump? If I need a pump, what kind do I need?



Will something like this work somehow?



Northern Industrial Transfer Pump Portable Diesel Fuel Transfer Pump — 12 Volt, 10 GPM | Air-Operated + Electric Pumps | Northern Tool + Equipment





TIA, Joe

 

[DennyDay]

First things first -



1. The quality of the tanks are not bad, but I don't know about off road twisting.



2. Depends on how much junk you want to carry in bed, I personnaly don't like the "L" tanks, and use a verticle tank that carries 55 gallons, between that and the 35 gallons in the origional, its now larger than my kidneys.



3. The Northern tool pump is to large for my taste, I use a regular fuel pump like the transfer pump,plus a 2lb. check valve to prevent siphoning, thru a 3/8" filter and feed it into the fuel filler tube in the truck. I put a dip leg made of 3/8" SS hard brake tube in a fabricated bushing in the top 2" fitting on the tank top. Also I fabricated a 3/4 fitting so I could install a vapor line between the tanks. I just cut the OEM vapor line and put a "T" in the line so I would't create a vacuum in the aux. tank. I installed a 3/8 hose barb fitting in the OEM fill tube about 6" down from the cap so I could see fuel transfering if I took the cap off.



I use a line voltage 15 minute timer (Spring wound) so I won't forget to turn it off plus a green light on the dash when the pump is on.



To transfer fuel, set the time for about 5 minutes when the OEM guage is below 1/2 and see how much fuel is transfered in that period of time.



If you have any questions, you can PM me for a sketch or pictures. It will probably take several days for me to answer you



Denny

 

[JCasper]

So maybe something like this and then I can still throw firewood under my toolbox.



Vertical Fuel Transfer Tank — 70 Gallon, Model# 72117 | Fuel Transfer + Storage Tanks | Northern Tool + Equipment

 

[DennyDay]

That one is similar to the one I use - - - Need to add more fittings to top unless you are going to use dispenser type pump. Fittings can be added by any good welder BEFORE fuel is put in tank.



Denny

 

[JCasper]

Why do I need more fittings on top? I don't know how to plumb a pump in, I will have to have some instruction on that.



Is it possible to gravity feed into the main tank since this one is higher?

 

[rweis]

I am experimenting with the Northern Tool gravity feed check valve. Not totally thrilled. I run DD'2s and gravity feed will feed them towing heavy + a tiny bit more. I fed 55 from bed and only gained 1/4 tank in the OEM. I think a pump might be better.



To fill I fill totally full OEM then bed tank. My bed tank is vertical to save bed space.



I did mine mainly for towing range.



Bob Weis

 

[JCasper]

One of the guys I work with was telling me that his dad had a in bed tank that he gravity fed in to the main tank. That's where I got the idea.



With his old Dodge which was a V10 he would flip the switch at about a 1/4 tank and it would gravity feed enough fuel that as long as he kept driving he would end up with a full tank about the same time his auxilary tank was empty. I am not sure how big the extra tank was, somewhere around 50 gallons I think.

 

[JCasper]

I am experimenting with the Northern Tool gravity feed check valve. Not totally thrilled. I run DD'2s and gravity feed will feed them towing heavy + a tiny bit more. I fed 55 from bed and only gained 1/4 tank in the OEM. I think a pump might be better.



To fill I fill totally full OEM then bed tank. My bed tank is vertical to save bed space.



I did mine mainly for towing range.



Bob Weis

I can't find one of those check valves, could you point me towards one?



Thanks

 

[rweis]

After a 3k mile trip towing our 13k 5er I have found that the Northern Gravity flow check valve will BARELY keep up with DD2's and extremely slowly fill the OEM tank. If you have larger than DD2's I would think twice about the Northern Tool gravity feed check valve.



I am going to let it go until I go to Mach 4's then go to an electric fuel transfer pump so I can fill the OEM tank as I need it.



Bob Weis

 

[steved]

I'm using a Summit Racing fuel pump (similar to a Holley blue) to push fuel through my small spin on filter (FS1251)... the setup will gravity flow (unless my siphon is broken) and keep up to normal driving without pumping.

I have found my 10 micron filter will start to impede flow after about 10k miles of use... and that I will need to "catch up" using the pump... I have only had the setup in use for around 20k to date (I'm on my 3rd filter)...

I don't think I would be happy only having a siphon/gravity setup (without pump)... I found that gravity feeding will only fill the tank so full and to be consistent, I need to pump fuel into the main tank when I fill the aux.

As a side note, I only have a 22-gallon cell. This is not nearly as big as some (but as noted) 22-gallons at 20 mpg is 440 miles and more than I can stand to sit at one time. I installed mine as a pre-filter more than an auxilary tank... after getting over a gallon of H2O in my fuel from ONE truckstop, I got paranoid...

steved

 

[rweis]

I do not at this time filter the aux tank because I have a pretty large filter / water seperator from the OEM tank to the fuel system and a second filter only just before the VP44.



That said, one of the problems I had with the gravity feed system is that I also totally changed the fuel level sender to a mechanical one (Tempo) with a remote reading capsule (more on that is in another thread). But, sealing the remote sender (installed in the step just forward of the cannister on an 02) has been a challange. I am using commercial sealing gaskets and backing plates, but still get a little seepage at the point I installed the remote sender in the OEM tank, not a perfect seal.



Using the gravity feed system the point of seepage is always in contact with fuel until the aux tank empties and the OEM tank feeds on its own. With a small pump system I could install a filter / water seperator between the aux and the OEM tank and only pump fuel when the OEM tank fell below say 1/2 tank then fill up to 3/4 on the OEM much like the Transfer Flow system uses. That would take care of the seepage problem and would add a filter / water seperator to the system. It would also take care of a problem that the gravity feed system does not feed fuel fast enough if I went to larger injectors.



The pump system to get the fuel from the aux tank to the OEM tank is I think a better way overall than the gravity feed system, and probably why Transfer Flow uses that system.



On refueling right now with the gravity flow system I fill the OEM if it is not already full, then fill the aux. That insures a full load of fuel. A pump would allow you to manually make sure the OEM was full, and do that fairly quickly. Gravity flow may tank hours depending on fuel usage (load, speed etc).



Bob Weis



I wonder about the circuit Transfer Flow uses. If fuel gauge resistance is less than xx turn the pump on until the resistance is above yy then turn the pump off. I wonder where you would find a circuit like that?

 

[steveinaz]

I have a 98 gallon tank in my 2005 and a 70 gallon tank in my 1993. Both are gravity fed into the filler neck with no check valve. Both have vents. Before I did this I heard all kinds of stories why this wouldn't work. None have proved true. I just took my 05 on its second trip to Newport Wa. I never stopped for fuel and I was pulling a 23' travel trailer. Both are longbeds so bed space is not missed.

 

[JCasper]

I have a 98 gallon tank in my 2005 and a 70 gallon tank in my 1993. Both are gravity fed into the filler neck with no check valve. Both have vents. Before I did this I heard all kinds of stories why this wouldn't work. None have proved true. I just took my 05 on its second trip to Newport Wa. I never stopped for fuel and I was pulling a 23' travel trailer. Both are longbeds so bed space is not missed.

I have not looked at the filler neck yet, how did you plumb into it?







If I understand correctly, you have NO valve and it feeds right into the main tank as needed.



I find that hard to believe that that works also. I would think it would overflow.

 

[steved]

I have not looked at the filler neck yet, how did you plumb into it?







If I understand correctly, you have NO valve and it feeds right into the main tank as needed.



I find that hard to believe that that works also. I would think it would overflow.

I have mine plumbed into the fuel filler neck also... since I already had the FASS, I simply took their manifold out, drilled/tapped it for the fitting, and reinstalled it... I thought if anyplace, you'd lose it out the vents in top of the tank (I have a 3rd gen).



I have yet to lose a drop and, from comments from others, haven't heard of it being a problem. I only get in trouble when it sits overnight and I try to see how full the OE tank is... I usually spill about a cup on the ground (you'd think I'd learn)...



steved

 

[dezeldog]

I have a system similar to steveinaz and it has worked flawlessly for over 2 yrs. I have a 50 gal aux tank that is plumbed to a ballcock valve then to a 2mic. racor FF/WS and then into in main tank. I have the vent bomb from 'spooled up' so I just used the oem vent that is not used after the vent bomb is done. It is gravity fed with no seepage probs at all. Hope this helps.



Jim

 

[steved]

I have the vent bomb from 'spooled up' so I just used the oem vent that is not used after the vent bomb is done.

I tried using the OE vent as well and found there might be a check valve that prevented using it as a connection... I ended up using the filler neck instead after using the vent didn't work for me...



steved

 

[steveinaz]

I have not looked at the filler neck yet, how did you plumb into it?







If I understand correctly, you have NO valve and it feeds right into the main tank as needed.



I find that hard to believe that that works also. I would think it would overflow.

It never overflows. Because it flows into the filler neck and the filler neck goes into the tank below the high level in the tank. With the cap on the tank and the gravity flow going, the upper portion of the filler neck will build up a small amount of positive pressure and stop the gravity flow.



I cut the rubber filler neck hose under the bed. I found a piece of tubing the correct diameter and tapped and sealed a #6 JIC fitting in the tubing. A simple 3/8 hose barb would work the same way. I used JIC fittings because I can get them from work. I did install a 3/8 ball valve up next to tank for safety but have never used it. The vent on the upper tank is important in Az in the summer time because the thermal expansion will create more pressure than what occurs in the filler neck and fuel will be pushed out the vent in the lower tank. Hope this helps. SteveinAZ

 

[PRout]

Use the OEM fuel pump to pump from the aux to the main through a decent filter. Put a switch with a timer to run the pump so you dont forget and leave it running.

Or do like I did and run it from the aux tank, to the oem pump, through a frantz filter and then to a valve to either a. ) circulate it back to the aux tank (cleaned by the frantz), or b. ) transfer to the main (also cleaned by the frantz). Works pretty decent.

 

[JCasper]

Back to this. I wasn't able to get one last year before our big trip, but want to get one this year.



I am thinking of going with the L-shaped tank still.



Transfering the fuel however I am still not sure how I am going to do it. I may just pick up an electric fuel pump of some sort and mount it to the inside of the bed of the truck and use it to pump to the filler neck.



I would rather gravity feed, but haven't figured out how to do that yet.



Joe

 

[PRout]

Had mine set up to gravity feed for about 2 yrs. It worked so-so. It fed pretty slow, and since I had an inline filter, it got slower and slower to the point where I couldnt feed the main fast enough to keep the fuel level up while towing heavy for long distances. Ended up revamping the setup and as already mentioned, used the oem lift pump pushing through a frantz filter for transferring fuel. It works out much better with the pump/filter combo. One thing to make sure to do (lesson learned) is make sure you have a shut off valve right at the tank outlet. It will come in handy sometime. .