This is an issue for me because I am in the process of working out a way to plumb the auxiliary tank I just finished installing under the toolbox in the bed of the truck. It seems this would be doable by simply swithching a selector valve to draw from the aux tank until the main tank is re-filled by the return, then switch back. Just wondering how long that might take.

I guess I'm wondering if this is something I'd do waiting in a parking lot somewhere, or while watching the fuel gauges as I driving down the road?

 

I have no idea, but just to give you an idea, the 06 cummin has at least 450 ml@ 60 sec.run(fuel return volume)

It would be real simple to check. Just disconnect the fuel return line form the eng, were it connects at the frame rail, and shove a hose on it........preferably a clear one, so if you ever have a question of air in the system you can us the same one.
Go into the kitchen and still a clear, glass, measuring cup(one that will hold atleast a couple of quarts) put the hose in the cup, and start the truck. Let it run for atleast 30 sec, to a min depending on how much flow you get.
If you can get a minute of flow, then all you have to do is times it by 60, and you have your gal.per hour fuel return flow!

 

Where'd you get those numbers, Flash? Just doing the math, it looks like to be about 15.2 oz./minute. So say 25gal = 3,200 ounces divided by 15.2 = 210 minutes! So, by that calculation it will take about three and a half hours to put 25 gallons back in the main tank! That will work well. Assuming the numbers are correct, of course! Somehow I doubt the 06 numbers will correlate very closely with the 1st gen numbers. Math never was my strong suit.

 

Ya, got my numbers mix around.....but is still going to be close!
the lift pump pushes 450-500ml @ 10 sec run.... The inj return is up to 160ml @60 sec run, The hi pressure pump return is 600-1000ml@60 sec.
in short, when the 06 is new the flow is 60ml(inj return)
and 600ml@60 sec.... total 660 ml

when you said 15.2 oz./minute......well i had to go get my favorit glass, measuring cup and......you are right on!!

 

In think all we got is the VE return, whatever that is...

 

we still have 2... inj return and the VE pump return that tee at the back of the block and then go to the frame rail.

 

OK, I only started installing the valve yesterday and haven't actually traced out all the lines. I'll just go with it like I planned, see how it does and report back. Only possible drawback I see is forgetting about it while it is running on aux during a long trip and over-filling the main tank. I wonder what would happen, probably just leak out a vent somewhere, depending on how the tank is vented?

 

if your new tank is 25 and your original is 30 and you waited till the low fuel light came on,you would be fine.............You could probably sw it over a about a 1/4 tank considering you wouldn't be running that tank dry(2or3gal,)the fuel you consume in the 3.5 hours(10 gal) considering that you were getting 20 mpg and travaling 60 mph...your original tank would be filled or would reseeve 12 gal.
These numbers are all theroritical but you may acualy be able to sw at half tank!
I think that you idea may just work vary well!!!
let me now how reality turns out!

are you going to be puting a fuel guage in the spair tank?

 

I recently picked up a W-250 with a 43 gallon aux tank in the bed. This was plumbed into the system using a fuel selector switch that had return line capabilities. I believe it is this item here http://pollak.thomasnet.com/viewitem...lve?&forward=1
I hope this info helps some

 

Thanks neko, but I already have the valve and unfortunately it is for one line only. A 2-line valve would make it alot simpler, at least from operational standpoint. Flash, the aux tank is 50 gal., and yes it will have a gauge. I was hoping the return flow rate was slower rather than faster, so always returning to the main tank would not present much of a timing issue and that seems to be case. So basically it looks like it will just be matter of keeping an eye on the gauges whenever running on aux. Heck, that's standard procedure anyway right? Keeping an eye on the gauges?

 

I have a big auxilliary tank, 52 gallon, along with two 20 gallon factory tanks.

For years and years, I have had a manual selector-valve on the draw line from the big tank, with no return-line to the big tank.

I run a stock tank empty/low, then switch the valve to the big tank, keeping an eye on the gauge, while cruising down the road.

It is very important to remember to switch off the big tank, when idling for any more than fifteen minutes, as it might over-fill the stock tank and pump fuel on the ground.

Also, even with the engine off, the fuel will continue to transfer from the big tank; so, when leaving it parked overnight, be sure to switch off the big tank.

All of this can also be taken care of by using one manual valve to switch the draw lines, and a second manual valve to switch the returns; then, the auxilliary would function in the same manner as the stock tank.

As to the time it takes to refill a tank, while driving, I can switch to the big tank and drive with it, while refueling a twenty gallon tank, depending on the load and terrain, and the gauge come up to full in from 40 to 60 miles.

I have never actually timed it, just sitting idling; but, if the stock tank shows 3/4 on the gauge, and I forget and leave it idle on the big tank, it will run over, before I can eat a Whopper and fries; don't ask me how I know this.

 

That's some real good info bearkiller, thanks! I guess the reason it behaves that way is less fuel is returned when the engine is under load. What happens when it runs over, is there a vent somewhere it comes out of, runs down the side of the truck from the fill opening or what?

 

Hi ACE!
when i bought my truck it had a 100 gal tank in the bed that had a manual ball valve that let the fuel gravity feed to the filler neck and when i would for get to close the valve on time it would leak till the filler neck was drained.

there or vent toobs ontop of the tank that i think was were the fuel was coming from!

remove the tank for more bed space, and kinda (some time)wish that i hadn't now.

 

Wow 100 is alot, that would take up some bed space! Mine fits just right under the toolbox, so I'm good with that. I considered doing the gravity feed thing, but I decided to plumb a feed through the selector valve to the LP so I can I can basically just switch and drive on without having to worry about it too much.

 

Ya it would squat the back end of truck pritty good when full! Not that i didn't squat before u fuel it!
PO cut and made a door so that you could fuel the tank thru the camper shell!