is it possible to add a second fuel tank

I was wondering about a 55 gal. Barrel they are easy to find around here.

Update on aux fuel tank:
I bought a new 42 gallon tank that fits 92-97 suburban. Went to salvage yard and got wiring, straps to hold up tank, filler hose and cap, fuel lines, and bought hoses to extend fuel lines. I have installed tank, installed and wired gauge into dash, new fuel pump in tank, wired. now just need to connect hoses , and finish filler tube. Fill tube is a bit of a problem, but bought 2 inch exhaust pipe, and will fabricate part of filler tube from that.

Before I did all that I replaced some sensors on engine, EGR valve, O2 sensor, plugs and wires. MPG went from 5.92 to 10.35 at 60 mph,on cruise, no toad. if that keeps up I could get by with one tank!

"A good metal fabricator can to any thing."

Yes, Femail, they can. But is it safe? In a collision? On a bumpy dirt road? Oh! The fabricator isn't sure...as in training? Experience?

I think the E350 got the 55 gallon tank in '97 when the V10 came out. They still have a 55 gallon tank today.

I put one in my 1977 Class C. Frame rails were the same width, but a little different. I used the hangers and straps from the new tank. Had to make some spacers as I recall to get it hung correctly. Mine was carbureted, I had an external pump, so just a pickup line in the tank. You might be able to just use the intank EFI style pump found in the big tank?

tderonne, if I can find a 55 that will work for me it would be great. Do you know what year model you got it from? My rv has twin I beam suspension on front, and as I understand it F53 has a straight axle.

I should also point out, it has a low pressure fuel pump in tank, and a high pressure fuel pump on the frame, near the engine area. So any tank I put on will need to work with my type tank pump/assy, or with a low pressure in tank unit of differnt year model.

I really appriciate all of the replies and suggestions

westtexus wrote:
Really, I should fill with fuel and water, load like for a trip, and weigh it. Compare to Max weight rating, go from there.

Good plan. Make sure you have chairs, grills, clothes, food, beverages, coolers, ice, everybody riding in it including pets, etc., too when you weigh. And don't forget to add in for the holding tank(s) in case you don't have an opportunity to empty them before leaving the campground.

Do you really have an E350 chassis? Do you mean F53? E350 would be a stripped van chassis, which has only been used under Class A motorhomes a few times that I know of. Your tank size does seem to agree with it being an E350, I think all F53s have either 75 or 80 gallon tanks. I need ot google your motorhome, maybe I can find some specs and learn something.

I swapped a later 55 gallon E350 tank into my older E350 that had a rusty metal box that had about 30 gallons working capacity. It was a GREAT upgrade. 200 miles between fillups really stunk.

Edit:
Hmmm...
Google seems to agree, E350:
91 Flair chassis

As I recall the 55 gallon tank is junk longer than the 35. The 55 looks like this:

(Not a Ford tank, but similar.)

Some action shots of a tank removal

Really, I should fill with fuel and water, load like for a trip, and weigh it. Compare to Max weight rating, go from there.

It's all about space
If there is room for a larger replacement, or an empty spot for another add-on

I feel sure it can be done...with enough money and ingenuity, you can do almost anything! My major concern would be the additional weight on a chassis most likely not designed for it. Consider the weight of the additional or bigger tank PLUS the additional weight of about 6lbs/gal of gasoline. It can add up fast. Just something else to consider before you get too far in your planning.