My 85 XJ Pioneer is needing a new Fuel tank since the old one is rusted out. I believe the one on it is the 12 gallon tank(I put about 3 gallons in it while working on the engine and it read 1/4 full). I was wondering if the 20 gallon tank will fit as it is or if there has to be any mods made. I was thinking maybe will need different size straps but maybe the larger tanks are just wider?

Thanks for any help.

 

The 13.5 and 20 gallon tanks both have the same dimensions. Easy swap.

 

are the 13.5 gallon tanks the same depth? I cant see how they can be the EXACT same dimensions

 

They both held 20 gallons. The 13 gallon one just didn't have a tube going all the way to the bottom. IIRC, we just swapped out senders as an assembly and voila, a bigger tank.

 

Boy, Jeep did some dumb stuff.

 

Dumb like a fox.....

 

If they are exactly the same size then why do the after market ones have two different prices, shouldn't they just be the same part numbers if only the sending unit is different since you are not getting the sending unit with the tank?

Is it also true for the vehicles with the mechanical fuel pumps like mine?

 

The funny thing is that it is cheaper for the manufacture to build the bigger one because it doesn't have that extra "stopper" in it. When one pays for the optional "bigger" tank, Chrysler saves on a cheaper design and make more money because its an "option".

That's great thinking... if you are in that kind of racket.

 

I don't know why. I can tell you that at some point we were able to convert 13 gallon to 20 gallon tanks by changinf the pickup unit. It all started when we got an XJ in that didn't have the large tank, which we always specified. Someone screwed up in Sales so we had to make it right. When going into the catalogs, we found the tanks were the same.

 

Very interesting. I just did some searching for prices online. At Advanced Auto they have the Spectra Premium in both 20 and 13.5 gallon sizes, and yes exact same dimensions for both, but the 20 gallon one is about $15 cheaper. I guess I know which one I will be getting. I just wonder now which pickup I have and if I will be getting a full 20 gallons I can use or if I will need to change the pickup to use it all.

I wonder if the pickup tube could be modified to reach the bottom of the tank if it is just too short?

 

so with the 13, do you have 7 gallons of gas just hanging out in the bottom of your tank at all times?

 

Think so.