I got the idea from Cory (ziggy) and I really like it... the kicker is, I really don't wanna have to use a valve or install pre-valve pumps to make it work. I want straight fuel all the time. So, I was thinking about taking both of the tanks and installing sumps underneath them and having them connected "in parallel" so it'll be one body of fuel. I would think that if my connecting hose were about the size of my filler hose (a little smaller would still work) so that it could flow fuel as fast as the pump is putting it into the tank, then the two tanks would fill up as one volume, right? Here's an illustration:



Basically, I'd fill the tank like normal from the main front tank and then the two tanks would fill up as one volume. I would either pull fuel from the front and return to the rear, or utilize the sump for a better supply of fuel to the pump. The thing is, I can't wrap my mind around the physics of the whole thing... I keep thinking of the cat waterer that we have that uses and upside-down bottle to keep the bowl full. However, that bottle doesn't have any means of breathing like the tanks do... would I end up having the same affect as the waterer or would both tanks fill as one volume? If it would work this way, I think I'd have the ultimate fuel setup... then when/if a flatbed happens, I'd add a transfer tank that feeds directly to the main tank below (same idea... have the filler necks of the lower tank feed into the bottom of the transfer tank)... talk about miles! So, what're y'all's thoughts on this? I know some of you guys are good with this stuff... my goal by doing this is to have a dual-tank setup that doesn't need any pre-pumps or valves. My reasoning is because I don't wanna have issues with the valve crapping out on me when transferring between tanks and I don't wanna have any air or anything getting into the lines between transferring either. Thanks, guys! I can't wait to read you opinions! POST UP!!!

 

You would need a vent on the rear tank to keep from the cat waterer affect.Without the vent fuel wouldn't flow to or from the rear tank
Both tanks will also have to be at the same level at least on the top
To fill both tanks from one filler the connector hose would probly have to be about 1"

 

Right, and both tanks have breathers already. As far as being level, I know that both end of the frame are the same height and the tanks are hung on about the same level. As for which is deeper, I'm assuming the excursion tank is... whichever is deeper would be the one I'd pull from and I'd let the shallower tank be the return tank. Sounding about right?

 

What if you parked on enough of an incline that the fuel ran from the main tank to the rear tank.....starving the pump of fuel. May only be a problem when getting low on fuel

 

not sure if your ask'n for "other alternatives" or making your idea work, but if i recall, when i did the "hutch" mod, there was 2-top fittings on the main tank, not being used. What if you feed the main tank, with the aux tank, by means of another pump, thats on a switch, using ofcourse, an inline filter, before/after the pump.

In regards to filling the aux tank, keeping both tanks perfectly level, would be the key. If achieved, then the attachment line, i think, would need to be mounted at the bottom of the tanks, but on the sides. If using bottom of main tank, to feed, top of aux tank, think the pressure of the main would keep filling aux tank to the point, it would overfill the vent line.

If achieved with connecting both tanks from the bottom, side, then my first paragraph wouldnt come to mind.

 

True, but I do still have the fuel bowl... I might rig it so that it pulls from both tanks equally. Good thought...

 

Right, I know I could do that too... I'm just trying to do it so I don't have to have more than one filler neck and so that I also don't have to worry about multiple senders. But yeah, that could work too... I would like to try to get the whole system to be the least "user-interactive" as possible if that makes sense. But yeah, that'd definitely work!

 

The only thing Jon other than what Shawn mentioned about parking on an incline, would be that the ex tank as you said is a little deeper, and I would be cautious about putting a sump on the bottom of the tank, My truck sees some serious offroad sometimes and i've put plenty of scratches on the tank guard. That is another thing too, the ex tank sits down in the guard. But then again, most trucks don't see the offroad situations that my truck does either lol.

 

True... guess I could always have it go into the side of the tank right on the bottom edge, right?

 

I agree with Ray, you would need a fat pipe along the bottom if you were going to fill both tanks as one.
And a second air pipe joining the tops of both tanks.

 

And it wouldn't be very practical in hilly country.

 

Would that be necessary if both tanks already had breathers on top (which they do)?

 

True, but with the rear tank being alot deeper than the main tank, wouldn't that be pretty much eliminated if I pulled from the rear tank? What about an "external sump" to hold fuel to make up for that? I have an in-line fuel filter that might act something like that... I don't know, I'm just thinking. I still don't know how it could be an issue with the main tank being as long as it is... I would think that if hilly country was a problem, the length of the main tank would be too which it's not. Doesn't the fuel bowl help make up for a bit of that? Just thinking out loud here...

 

You talking about the rollover valves? I don't think they have adequite volume to handle venting while filling up.
If I were to do something like you are suggesting, I would run a 1 inch pipe on the bottom and a 1/2 inch pipe along the top with a tee in the middle of both and a vertical pipe between the top and bottom to eliminate any chance of pocketing.
But I still would recommend against doing something like this. Fuel pump draws from the front tank and you are down to less than 1/8 tank and now here is a big hill to climb.
All the fuel will run to the back tank and starve the fuel pump.
Unless you ran the 1 inch pipe from the very front of the tank so that if you had to climb a hill with low fuel, that escape route for the fuel is cut off until you level out again.

 

Sorry for the threadjack, but if anyone needs an Excursion fuel tank, I have an extra one. Shipping might be an issue though, since it had gasoline in it. Same as the diesel tank AFAIK, except for the pickup assy.

Now back to physics class...