Fuel tank crossover

Topic: Fuel tank crossover (Read 657 times) previous topic - next topic

Fuel tank crossover

August 12, 2016, 10:05:27 pm

On our 96 U320 it has 2 fuel tanks next to each other, 1st tank for gen & Aqua Hot 2nd for cummings. It use to have a crossover at bottom of the 2 tanks, never used it and one day one of the fittings cracked and I removed crossover and capped off both tanks.
I thought it would be nice to put back to factory, So I installed 4 new JIC fittings with 1/2 inch fuel line Question is 1st tank holds 55 gallons - 2nd holds 190 gallons the larger tank with crossover valve open will it level up or tank larger tank overcome smaller tank, and when open will tanks drop evenly .

Re: Fuel tank crossover

Reply #1 – August 12, 2016, 10:14:15 pm

I would think it would react as water and level out especially if the caps are venting type!!
JohnH

Re: Fuel tank crossover

Reply #2 – August 12, 2016, 10:24:55 pm

Wow, a lot of diesel. You sure of those capacities?

Re: Fuel tank crossover

Reply #3 – August 12, 2016, 10:56:54 pm

The fuel will seek it own level just like any fluid.
Just be sure that the tanks are level with each other on the top, if it worked before it should work again.

Re: Fuel tank crossover

Reply #4 – August 12, 2016, 11:43:11 pm

If you leave the valve open it will act as a single tank. The level of each will be the same. Only time they might vary is if you are filling up the big tank (say at the truck island where the nozzles are bigger) and the cross-over hose can't transfer the fuel as quickly as it's filling. Just opening the fill cap on the smaller tank will help it transfer faster so the displaced air doesn't need to go through the small vent tube at the top of the tank.

I would guess it was a special request the original owner made when ordering the coach. I was scratching my head trying to figure out why they wouldn't make one larger tank for the same space. Then it came to me: road tax. Original owner probably had an off-road (red dye) fuel supply source from his business or farm. You only need to use road taxed fuel for the Cummins. Separate tanks keeps the red dyed out of the main Cummins tank. The option probably cost way more than the savings in tax but I bet he did it for principle. Just a guess.

Re: Fuel tank crossover

Reply #5 – August 13, 2016, 12:08:19 am

Pretty sure of capacity some one wrote on each tank, and as per red fuel I sucked some fuel out of small tank and it had a red tint.

Re: Fuel tank crossover

Reply #6 – August 13, 2016, 12:29:45 am

Quote from: prevostart – August 13, 2016, 12:08:19 am

Pretty sure of capacity some one wrote on each tank, and as per red fuel I sucked some fuel out of small tank and it had a red tint.

Like it, present coach has same setup, nice not to worry about running out of fuel to main engine. Also easier to keep track of gen fuel consumption.
Jim

Re: Fuel tank crossover

Reply #7 – August 13, 2016, 08:57:33 am

See, this is why I love this Forum! Every time I think I've heard it all, someone pipes up with something I've never heard of. 2 fuel tanks - COOL!

Re: Fuel tank crossover

Reply #8 – August 13, 2016, 10:10:56 am

Quote from: Chuck & Jeannie – August 13, 2016, 08:57:33 am

See, this is why I love this Forum! Every time I think I've heard it all, someone pipes up with something I've never heard of. 2 fuel tanks - COOL!

Foretravel thought of it in 1981. Mine has three tanks, one 100 gal. for the generator and heaters and two 100 gal. tanks for the engine. There is no connector between the single tank and the engine tanks but a small connector between the engine tanks. Had to fill at all three fill points because of the small connector.

Re: Fuel tank crossover

Reply #9 – August 13, 2016, 10:24:01 am

My primary concern with two tanks is that the smaller tank may allow fuel to really age if aquahot and generator are not used enough.

So, may want to add a biocide such as Biobor JF.

Re: Fuel tank crossover

Reply #10 – August 13, 2016, 10:32:03 am

and if valve is open and red diesel is in the small tank, it will contaminate the big tank...the chances of ever being checked are remote but fines are really stiff if it should happen.

Ralph
96 U270

Re: Fuel tank crossover

Reply #11 – August 13, 2016, 10:41:58 am

That's why I think Foretravel installed crossover so you can also use both tanks so fuel does not get old, Both tanks are around 1/4 tank last thing I did a couple of months ago was siphon fuel out of small tank and add to lager tank, that's when I noticed red diesel fuel, now when needed I will open bypass and add to lager tank or leave open and use both.

Re: Fuel tank crossover

Reply #12 – August 13, 2016, 10:47:34 am

The lack of a crossover between the separate 100 gal. tank on my '81 was to prevent the generator and heaters from running the engine out of fuel while dry camping. It being all electric the generator was used a lot.

Maybe that was the reason for the smaller tank on yours.

Re: Fuel tank crossover

Reply #13 – August 13, 2016, 11:45:32 am

With the multiple fuel tank installations, is there a separate fuel gauge for each tank?

Re: Fuel tank crossover

Reply #14 – August 13, 2016, 12:07:51 pm

Quote from: Chuck & Jeannie – August 13, 2016, 11:45:32 am

With the multiple fuel tank installations, is there a separate fuel gauge for each tank?

On the '81 it had a switch to show the level of the 100 gal. tank and the other two 100 gal. tanks. One gauge 2 senders, the 2 tanks equalized out after filling and they were set at the same height on the frame.

Re: Fuel tank crossover

Reply #15 – August 13, 2016, 12:22:17 pm

I thank I was wrong on the quantities , just put fuel in and large tank said 1/4, It took 70 gallons so I would thank it is a 100 gallon tank, small tank said 1/3 and added 20 gallons and it's almost full so I think it's a 50 gallon tank?

Re: Fuel tank crossover

Reply #16 – August 13, 2016, 01:21:01 pm

Looking at those tanks in picture those figures do not seem right. The small one looks to be a 1/4 or less the size of big one.(in width anyway?
JohnH

Re: Fuel tank crossover

Reply #17 – August 13, 2016, 01:33:46 pm

The small tank is bigger in rear check out picture.

Re: Fuel tank crossover

Reply #18 – August 13, 2016, 01:36:49 pm

Quote from: prevostart – August 13, 2016, 01:33:46 pm

The small tank is bigger in rear check out picture.

THAT is what you call taking advantage of every spare cubic inch of space!

Re: Fuel tank crossover

Reply #19 – August 13, 2016, 02:08:34 pm

wow, thought the main tank like most others was full width!! Wrong.
I would rather have the regular set up of one tank, but then we do not need a generator (or should I say do not USE it, except to exercise it now and again.
JohnH

Re: Fuel tank crossover

Reply #20 – August 13, 2016, 02:47:40 pm

150 sounds right. That is what most of the single tanks are

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