i have a 79 f-150 4wd w/ dual tanks.. my question is will the front tank for a rwd work? what if any is the difference?

 

it "should" but you need to make sure it is from a similar year because there are a few differences between later and older models. (they still will work with a little creativity tho)

 

PT, your tank has emissions. You will need a tank with the extra line going to the Charcoal cannister. 78-81, and maybe even newer than that? I dont know about the 80's stuff.

You wont be able to use a tank out of a Pre-emissions vehicle. That's a 73-77.
Also the main difference between the 2Wd and 4x4 front tanks is the length. You cant use the 'longer' 2wd tank on the 4x4!

a word to the wise here. If you put in a used tank you may be getting a lot of 'stuff' in your fuel line.

Put in a 'See through' (walmart,AutoZone etc etc... $2.99) Filter down along the frame between the tank and the Valve.
You can readily see if your getting a lot of 'gunk' out of your 'new' tank.
Just replace the filters till they stay clean. Buy a couple of them when you buy. Keep a spare Handy.

I put a gallon of Diesel in my 'new' tank and swished it around for awhile.
Jeez you shoulda seen the crap that came outta there.
But the worst part, was after driving around for awhile, more stuff got shook loose and I had to change the 'see through' filter three times.

Whatever the chemical in the tank, plugged up my final filter on the carb as well. I changed that a couple times as well.

 

I use a giant steel high flow/high pressure fuel filter made by Fram. (it costs about $30, and it is biiig!) I use the clear cheapie at the carb too. It would take an act of congress to plug that big baybe. I have made a non emissions tank work on emissions vehicles before. The 77.5 and up 4x4 trucks can and will use the 2wd tanks, trust me, I know! The only odd thing was making the vent hose a bit longer to wrap around the fill tube because I used a '74 tank (non emissions) work on a '79. On the pre 77.5's the frame witdth is smaller, so the 2wd tanks wont fit.

 

I got a tank, then had to go back and get the Filler neck because they changed the vent hose from front to back.
I just leave the cap loose and dont fill it up.
I'm going to have to pull the tank down and replace the Sending unit on my tank.
I'll install the vent line and run it all the way up to a charcoal cannister.
All this stuff I'll have to find in the boneyards.

Sometimes I wonder if I'd be doing something important or productive if I didn't have this old truck to work on?

 

You can find a thread in the Garage forum about cleaning the rust and crud out of a tank. You can also tee an emissions line to the charcoal cannister off the tank vent line. Loop it up high to keep gas from flowing down the line. The cap can sometimes be replaced with a vented type. You can also cut a small groove with a hacksaw in the seal surface of the tank filler neck. If you strike a spark you may be very sorry tho...

Be SAFE!

 

The one about cutting a groove in the top of the fill tube.
I'd do that if I ever had that filler tube out of there, but therwise.....Nope!

Putting a Tee in the existing vent tube is a viable Idea.

I dont know what I'd make the actual Tee out of, but I'd use standard Stainless Brake fluid lines, and put a big anti-siphon loop back at the filler neck.
Thats one of those "Gee, why didn't I think of that?" Ideas.

 

You can get brass tee fittings with different branch and run sizes. You can also get steel tee fittings from Ford for use with heater lines etc. Use all SS hose clamps in those remote areas to keep bad things like corrosion from ruining your day.

Put the tee in the vent line down low and then run that loop up above the fill point if possible.

Putting a groove in the seal surface is a lot easier if the neck protrudes above the body surface

 

My '73 F100 2wd has the vented emissions tank with a charcoal canister mounted up front under the radiator (I'm the third owner - it's a stock setup). I got a used tank out of the neighbors dead '78 F100 2wd and it was exactly the same... but maybe 2wds are different than 4x4s...

Marty