1973 Wagoneer + 1980 Fuel Tank - whats needed?

[Dr. Marneaus]

Hi!

I'm sick and tired of patching the same dang leak on the original steel tank in my 73. The stupid vent tube at the front of the tank has a broken weld and it always leaks a few weeks after I fix it. tried putty, JB weld, more putty, more jb weld, cant get it to stay sealed very long.

I'm also sick and tired of having to crawl under there and get covered with gas every time i have to drain 3 gallons out of the tank to stop the leak and patch it.

If you cant tell, I'm fed up!

I've got a tank/skid out of a 1980. the plastic tank that mounts to the skid, and the skid mounts to the truck.

What is different about this tank and what will I need to do? Obviously i'm going to have to drill a bunch of holes in my frame rail to bolt up to, thats fine, thats what a corded drill and step bits are for!

Are the other mounting points the same? (i have one at the front, and one on the side by the drive shaft, then one at the back, i think).

I believe this is when they swicthced over the the fuel level/pickup being all 1 part, correct? Does this mean it's going to be the reverse polarity sending unit so my fuel gauge will no longer work? If so, how do I solve this problem?

Lastly, these tanks have a return line, correct? So i can just get a 2 pronged fuel filter and run a line back to the tank, thus helping to keep my fuel cool!

[csuengr]

Beer. Lots of beer.

[Dr. Marneaus]

well DUH. Ca-mon man, this ain't my first rodeo!

[FSJunkie]

Hi!

I'm sick and tired of patching the same dang leak on the original steel tank in my 73. The stupid vent tube at the front of the tank has a broken weld and it always leaks a few weeks after I fix it. tried putty, JB weld, more putty, more jb weld, cant get it to stay sealed very long.

I'm also sick and tired of having to crawl under there and get covered with gas every time i have to drain 3 gallons out of the tank to stop the leak and patch it.

If you cant tell, I'm fed up!

I've got a tank/skid out of a 1980. the plastic tank that mounts to the skid, and the skid mounts to the truck.

What is different about this tank and what will I need to do? Obviously i'm going to have to drill a bunch of holes in my frame rail to bolt up to, thats fine, thats what a corded drill and step bits are for!

Are the other mounting points the same? (i have one at the front, and one on the side by the drive shaft, then one at the back, i think).

I believe this is when they swicthced over the the fuel level/pickup being all 1 part, correct? Does this mean it's going to be the reverse polarity sending unit so my fuel gauge will no longer work? If so, how do I solve this problem?

Lastly, these tanks have a return line, correct? So i can just get a 2 pronged fuel filter and run a line back to the tank, thus helping to keep my fuel cool!

You can't JB weld them and expect it to seal for more than a few weeks at best. Gasoline is a very effective solvent and can eat through most anything.

Gotta weld it, no way around it. My gas tank has been crushed up against the floorboard by rocks multiple times in the last 40 years and I managed to salvage it. It seals so airtight now, the entire fuel system will hold pressure overnight, which is what it's supposed to do for vapor recovery. I put serious thought into a new poly tank, but they mount completely different and do not have the large filler extension at the back of the tank, adding more complication. The filler vent is not on the side of the tank, but at the rear. Odds are it wouldn't work right and would back up fuel. the poly tanks don't have the three vapor recovery lined, so if i couldn't modify my vepor recovery system to work, it wouldn't have one and would vent gas fumes like crazy.

If the poly tank approved for the pre 1979 vehicles are so hard to make work like I stated above, I don't want to think about what adapting a 1980 and later tank would be like.

It'll hold fuel, but more power to you to get the filler and filler vent set up so it doesn't back up and to adapt the vapor vents to your charcoal canister to control stink. I hate fuel stink.

[babywag]

I looked @ doing this on my '73 w/ an '89 tank.

My tape measure and eyeballs told me it(new tank) wasn't going to fit.
This was years ago so my memory is fuzzy, but there was more than 1 issue that stopped me from trying.
Thinking it was transfer case & rear crossmember

I wound up using a '79 tank and matching skid, bolted right in w/ zero issues.

[tgreese]

You're going to have to take the tank out anyway. Why not take it to a professional and have it repaired? Old time radiator shops do these kinds of repairs. And I believe they will solder, not weld - it'll be plenty strong. Look around for a radiator shop that still repairs radiators. They are a vanishing breed. But there should be at least one or two in your area.

They can add a return line to your tank too, if you want that. Should be trivial.

90 seconds of Google searching turned up this - http://www.arrowheadradiator.com/

[Dr. Marneaus]

aitttteeeeeeeeeeeeee.

I suppose I can also have them install a bung for a fuel return line of some sort and get the best of both worlds.

And yeah, i'm aware of the issues of the poly tanks made to replace the older style steel tanks, which is why I wasnt going to go that route.

Also, I've just come to the conclusion that I'm always going to have fuel stink. It reeks in my truck, pretty much all the time, and I've never been able to solve that. It'll be fine for a while, but on hot days, my charcoal canister thingy gets saturated and it all wafts into the cab as I'm cruising around.

Other than that, when the tank isnt actively dripping, it's not bad, but it always happens eventually. Not sure what to do about that, everything is hooked up as it was OEM, including the vent lines, and the breather. Only thing thats different is my stupid air cleaner nose is cut short and im pretty sure it provides zero vacuum to the vapor canister.

Is there somewhere else i can hook it up and get the desired vacuum result?

[tgreese]

What?

[Atla]

Why don't you go ahead and drill/tap and install a drain plug?

I'd take it to a radiator shop as mentioned, they'll clean it out and patch it up.

[tgreese]

Why not get the correct air cleaner? Try the WTB board. I'd think any V8 air cleaner through the mid '70s should work, as long as it has the tube on the snout. My '75 CJ-6 has one like that, and a 3-connection canister. So '70-75 V8 with vapor recovery should be compatible.

[Dr. Marneaus]

I only have a 2 connection canister. Strange...

[tgreese]

I only have a 2 connection canister. Strange...

No float bowl connection. Purge to the air cleaner, vent to the tank. Same otherwise.

[FSJunkie]

I only have a 2 connection canister. Strange...

Some V8's purge the canister through the air cleaner snorkel, I believe this was 1973 onward and used the ventui effect through the snorkel to suck out the vapors. The other way was 1972 and prior. For automatic transmissions like mine, the purge line connects to the PCV grommet below the PCV valve. It is a special grommet with a vacuum fitting at the base. Only V8's with automatic transmissions got a canister like this. The manual transmissions and I6 engines, all transmissions connected the purge valve directly to the valve cover, without a canister.

You can't just connect the purge line to manifold vacuum. Since the canister doesn't have any restriction in it, it would create a huge vacuum leak. Without the original air cleaner, the best way would be to tie into crankcase vacuum like pre 1973. Otherwise without a way to purge itself, your canister will saturate and eventually go bad.

The system only works if it is completely air (and fuel) tight. The tank needs to seal, the level and fuel senders need to seal, the filler and vent along with the cap, the three vent lines, the vapor seperator in the rear quarter panel, the long line up to the purge valve, the line to the canister, and the line from the canister. If any of these are leaking or hooked up wrong, it can vent fumes either under the car (flame on), under the hood (flame on), out the gas cap (ehhh...), or into the passenger compartment (very bad), because some of the vent lines are indeed inside the passenger compartment just behind the cardboard cargo side panel.

BTW, this setup wasn't just for Wagoneers, trucks used the exact same setup just with an expansion tank insead of a seperator and there weren't any vents inside the cab.

Sealed and working properly, air enters through the gas cap, but can only leaves by one of the three vent lines, to the vapor seperator which seperates out liquid fuel, to the pressure purge valve, and if the pressure is high enough, the valve will open and vent to the canister. You can hear it hissing through the seperator in the cargo panel on a hot day. There is a safety over-pressure valve in the gas cap should the system fail and not be able to purge the pressure. the system does not work with a completely full tank of gas because the vent lines are filled with fuel, this is also when the gas cap valves come into play, and then the car stinks as it vents through the cap.

It's complicated and has literally dozens of hose connections to leak, but if you take some time to set it all up, your car won't stink at all, except for the carburetor after you shut it off. Most of the vapor vents are vinyl tubing and hold up pretty well, but they splice in several places and at each end with rubber hose and clamps. These are usually where they leak. Make sure they are connected to the vapor seperator correctly, since there are 4 lines to and from it.

[Dr. Marneaus]

Some V8's purge the canister through the air cleaner snorkel, I believe this was 1973 onward and used the ventui effect through the snorkel to suck out the vapors. The other way was 1972 and prior. For automatic transmissions like mine, the purge line connects to the PCV grommet below the PCV valve. It is a special grommet with a vacuum fitting at the base. The manual transmissions connected the purge line to the valve cover. Either way it relied on crankcase vacuum.

You can't just connect the purge line to manifold vacuum. Since the canister doesn't have any restriction in it, it would create a huge vacuum leak. Without the original air cleaner, the best way would be to tie into crankcase vacuum like pre 1973. Otherwise without a way to purge itself, your canister will saturate and eventually go bad.

The system only works if it is completely air (and fuel) tight. The tank needs to seal, the level and fuel senders need to seal, the filler and vent along with the cap, the three vent lines, the vapor seperator in the rear quarter panel, the long line up to the purge valve, the line to the canister, and the line from the canister. If any of these are leaking or hooked up wrong, it can vent fumes either under the car (flame on), under the hood (flame on), out the gas cap (ehhh...), or into the passenger compartment, because some of the vent lines are indeed inside the passenger compartment.

Sealed and working properly, air enters through the gas cap, but can only leaves by one of the three vent lines, to the vapor seperator which seperates out liquid fuel, to the pressure purge valve, and if the pressure is high enough, the vavle will open and vent to the canister. You can hear it hissing through the seperator in the cargo panel on a hot day. There is a safety over-pressure valve in the gas cap should the system fail and not be able to purge the pressure.

It's complicated and has literally dozens of hose connections to leak, but if you take some time to set it all up, your car won't stink at all, except for the carburetor.

So I need a non vented gas cap then and a correct snorkel and should be good because everything else seems to be correct.

Normally my tank vents out the gas cap on hot days I can hear it hissing. Some days it decides to spray about a quart of gas at me if I open it.

[FSJunkie]

So I need a non vented gas cap then and a correct snorkel and should be good because everything else seems to be correct.

Normally my tank vents out the gas cap on hot days I can hear it hissing. Some days it decides to spray about a quart of gas at me if I open it.

That's not right then. It sounds like the system is not purging to the canister and is building up pressure, causing the safety valve in the cap to go off.

I updated my post since you quoted me, you might find some more helpful information in it.

I'm making scans of my TSM where it outlines this stuff to post up for you.