Hey all

OK, so I have looked at a number of threads on this issue, including a few I researched & tagged for future reference a while back.

My goal: increase the fuel capacity of the 89 F350 Lariat w/ 460. Currently the rear tank is missing and I'm figuring out what I want to do with the spare tire.

I am considering a 19 gallon replacement tank + new sending unit + straps, but I think it might be worthwhile to go with a bigger tank. I have heard of some guys using a 39-gallon tank from a Bronco but I think it's a 33-gallon based on what I found at RockAuto. The difference seems to be about $20.

Currently I have the spare chained thru a corner tie in the bed to make sure it's secure and doesn't walk away on its own. Based on what I am hearing I may want to keep that setup. I would have to do a bunch of rust cleanup on the existing support arm, buy the locking mechanism for the support arm, as well as the large bolt & other pieces to secure the wheel. And then lots of people I have heard from really aren't thrilled with how it works when you need to use it nor happy with the locking mechanism.

It's an old truck so I'm thinking it's a safer bet that I'll need to swap a tire at some point than not. Especially for my son to deal with if he's on the road alone I am thinking we keep it in the bed not mounting it underneath. And that gives me the space the tire would have taken for a larger (deeper) tank.

Do I need anything other than the stock 33-gallon fuel tank assembly kit that would be for an 89 Bronco? Anything to protect the tank a bit better or make sure all the parts fit well?

The only thing I found wrapped in plastic under the truck (where I was expecting a sending unit) are the loose rear fuel lines etc. No unit. So I think I'd just need to connect those up to the newly installed tank/unit and strap it in. Am I missing anything?

 

There's a write up on here for the bronco tank swap. Searching would find it.
You'll have to fab your own skid plate or mod the factory one if you can find one or just use straps for a bronco.
Factory skid plate (frame is flipped upside down):


Another thing to consider is swapping a newer truck's tank in. The tank on a Super Duty is around 38 gal I believe and mounts where the front/side tank goes on our trucks. Pair with a 30+ Bronco tank in the rear and you have a lot of fuel to burn.

 

By modify the skid plate do you mean cutting / welding? I don't have those kinds of tools & experience to do that.

The truck is a 4x2 so normally wouldn't have a plate like that anyway. Carrying a spare tire underneath doesn't warrant a skid plate, but a big old tank full of gas might.

You mention just using straps for the Bronco. Is the installation setup to be the same between the two, just longer straps?

 

By modifying it I mean lowering the plates by way if how they attach. Perhaps threaded rod rather then bolts. Although that wouldn't prevent an impact with the side of the tank, but neither would Bronco straps I suppose.

The Bronco straps are just longer straps.

There's a Bronco skid plate also.

 

Without measuring, looks like the Bronco straps should fit. And they are much beefier than (what's left of) the prior straps the rear tank had.

I noticed today that the fuse for the 2nd tank is not installed in the fuse box. Is that the proper method to prevent use of a non-existent sending unit?

 

you can buy an aftermarket 32 gallon tank from JC whitney,

you have to modify the fuel pump.

https://www.ford-trucks.com/forums/1...tank-swap.html

I bought one for mine, but wish I had just had the got rid of the 15 gallon tank,

and bought a replacement 19 gallon tank,

I just have the 300 6 cylinder,