FJ55 evaporative emissions hook-up options (1 Viewer)

[BrianCB]

I have a Dec. 71 FJ55. Some time ago the fuel tank developed a vacuum that caused the tank to collapse inward from the top. A shop dropped the tank and pressurized it and managed to make it less concave but it still is caved in a bit. The problem I have now is when I go to fill it up, the vent tube in the inside of the tank is submerged with about 5 gallons left to fill so it takes quite some time to fill the last 5 gallons, otherwise I risk spilling gas. My question is, can I switch the vent tube hose with an evaporative emission hose? I can't really see where the evaporative emissions tubes end up inside the tank, does anyone know if they stay at the top or do they bend down towards the bottom of the tank? If all these tubes end as an open line in the tank, I'm assuming it's safe to switch them around, might that not be the case? The evap tubes are probably 1/3 the diameter of the vent tube, if I did switch one, would it not vent quickly enough so I just end up with the same problem in the end?

Thank you,
Brian

 

[AntFarm]

Can you hook up the vent hose to one of the evap tubes? I would guess yes this would probably work in principle. However if the vent tube is spilling liquid fuel then I would just plug it. Don’t route it to any hose that provides a path to the charcoal canister. Liquid fuel isn’t good for the charcoal.

 

[BrianCB]

The vent tube itself isn't spilling gas, it's just not working once it's submerged inside the tank. The gas is spilled because it's not going down the filler tube quickly because once the vent tube is submerged inside the tank, air can only get out the filler tube. So I've got gas trying to go in, and air trying to get out the filler tube at the same time.

But it sounds like you think it would be ok.

 

[AntFarm]

I would say, can’t hurt to give it a try. From everything I know about the Evap system I highly doubt that if you eliminate one of the three evap hoses you would have any detrimental effect. It will probably work just fine. As for the air venting out of a smaller tube? At the worst you might need to shut off the fuel pump a couple of times to let the air equalize but I’m guessing it will work. Give it a shot and report back.

 

[3_puppies]

did the problem start after the tank was re-installed?
does 1971 have the vent tube up along side the fill tube?
could who ever tried to fix the tank, leave the vent plugged, as they would have had to plug all holes to try and add preasure to the tank
not sure you'd get enough volume of air thru a small hose versus the vent hose, versus the volume of gas going into the tank
I'm thinking you have bigger issues, I've never seen a vehicle gas tank have that much vacumn to collapse the tank

 

[BrianCB]

It started after rebuilding from a major disassembly and restoration of the entire vehicle.
The gas cap has been replaced after the collapse and I haven't had any vacuum problems since then.
The vent tube attaches to the fill tube about half way up the fill tube.
The vent is definitely not plugged, I have the tank removed now and it's clear.

 

[Blastservices]

I feel like the tank I installed on my 73’ is a 71’ tank. Does yours have 4 breathers ? One on each corner? I think that maybe the reason the the tank collapsed inwards was because the fuel cap wasn’t vented. Now that you have the new cap that issue should be past you.
I have this tank style installed now.
The 73’ tank had four ports all lined up on a row on the driver side (left) . The vent has to be on the top of the tank to work. Maybe have to pull the tank down and really get that concave top back out somehow.

My truck I plugged all four vents and it takes fuel no problem but with a full tank the fuel expands and runs down the quarter panel. I just purchased all the Evap breathers so my plan is to install those.

 

[BrianCB]

The tank I have is like your 73, all the emissions ports are lined up next to each other, mine in a Dec 71 so maybe yours is earlier 71?

I've never seen a tank like the one in your picture (but I haven't seen that many). I've pulled my tank and bought a stud welder, I've been able to pull dents and creases out in a localized sense, but the overall "concaveness" is not so easy. I can pull it out, but it immediately goes back when I let go, so I'm not sure how to get the metal to go back to it's original shape without a very extensive and slow process of stud welding and slide hammering.

The concaveness I think is worse than it looks like in my picture. Or maybe I've helped it more than I think. LOL

 

[3_puppies]

you stated the vent is clear, how far into the tank does the tube extend?

 

[BrianCB]

The vent tube extends into the middle of the tank where the end hangs on a bracket just below the indent where I have welded 4 studs, just to the left of the wooden wire brush in picture.