Fuel tanks design

Different diameters

 

Need new tank straps and probably drilling holes to mount the new straps.

 

Both sides just have to be equal. All the fittings and even the length of the hoses.

 

Something as small as one tank having a draw or return line longer than the other side can screw up the whole deal. Maybe the longer hose is 4 inches higher than the other side. Are the holes in all the fittings the same size? A side draw mated to a top draw tank would likely be a problem.
There are numerous trucks through here with different size tanks. Some had a divider put in them for a hydraulic section. Others to work around DEF crap, pumps and such. Size does not matter in this case.

 

I have a FASS. I changed 1 leaky supply line on one tank with a different brand (from Eaton weatherhead to Parker hose-or something like that), both the same size-like #6 or #8, don't remember-and had diesel overflowing from one tank at the fuel cap after a few minutes. It would start overflowing pretty quickly if I just fueled up. I finally figured out it was because the new hose had a slightly different diameter than the brand it replaced. And I am talking like about 0.09 inch difference. Different size of holes and length in the fittings too. The return fuel line from the FASS ported and dumped into the top of the tank. So it drew more fuel from one tank than the other but returned an equal amount. When I would unplug the FASS, I didn't have an overflow problem, but the fuel guage would drop fast as more fuel was drawn from the left tank, but the return fuel from the head wasn't so much as to overflow the right tank. Fuel would reach equilibrium in tanks after sitting. Definitely best to use the same brand and fittings for fuel lines as well as lengths. And make sure the ports are the same distance from the ground. Long winded, I know.

 

Definitely not too long winded. I just bought new fuel lines from NAPA and he was going to make them both the same diameter even though the ones I brought in were 2 sizes (8 and 6, I think). My concern was volume, so he made them the sizes I brought in.

 

I am not sure of your point. I guess you are saying that you used 2 different sizes? There are different sizes on 1 tank- the supply line is larger than the return line. We are talking about making sure the supply lines match up, and the return lines match up.