Gas leak from tank area-- 1997 LX450

[sjpitts]

I walked out my door today and smelled gas. I looked under my 1997 LX450 and saw a pretty significant puddle of gas.

I had just filled up the day before, and maybe driven 30 miles since the fill up. So the tank is nearly full. And it is getting hot today.

I took off the gas cap, and there was a pretty significant "woosh" when I did, so the tank itself seemed to be under pressure. And it seems to be leaking less since I undid the cap.

It looks to be leaking from the front area of the tank-- close to the t-case. And it appears to be leaking from the topside of the tank.

My thinking is that since the tank itself was holding pressure that the leak is probably not in the tank itself. Otherwise, the tank itself would not under pressure. Does that sound right?

And does that mean the leak is likely either in the fuel line or return line? Or maybe the line to the charcoal cannister?

Any guesses-- educated or otherwise would be appreciated.

Thanks

 

[BILT4ME]

Very common issue.

You need to replace your charcoal canister with a VC120 or equal.

Also, you'll need to repair or replace your tank.

Here's one of the many threads about it.:

leaking gas from top of tank

forum.ih8mud.com

I recently checked and the fuel tank is P/N 77001-69036 and is $792.66 from Olathe Toyota.

 

[ChasquiOverland]

Your tank is crack you can buy a Dorman gas tank P#576-754 or get it weld

 

[Desert Dino]

Your tank is crack you can buy a Dorman gas tank P#576-754 or get it weld

Very difficalt to weld becus of the layer of rubber

 

[ChasquiOverland]

Very difficalt to weld becus of the layer of rubber

finding who can weld with tig on a gas tan is the trick not to many people wants to do it i saw tanks like fk40 or 60s that they used a a penny shape it and braze soldering and it holds

 

[Desert Dino]

finding who can weld with tig on a gas tan is the trick not to many people wants to do it i saw tanks like fk40 or 60s that they used a a penny shape it and braze soldering and it holds

80 OEMtank is different then older models, its 2 layers of thin metal and rubber in between sandwich

 

[ChasquiOverland]

80 OEMtank is different then older models, its 2 layers of thin metal and rubber in between sandwich

got it, not saying that is the proper way in all type of tanks am just saying that a i saw them holding

 

[bigredmachine]

mine leaked at the near the seam on the top half of the tank there was dirt and mud that wanst getting washed off and it just held moisture causing the rust. i was able to get it welded by a rad repair shop that we had used in the past for repairs or aftermarket rads. at the time i had it go as a ticket through the dealership i was working at and it only cost about 130 to get it done. if your going to drop the tank now would be a good time to replace the brake lines running along the frame

 

[LandCruisinMy93]

Oh yeah! Got yourself a Crack in the top right under the little rubber insulator in the compound curve area...I'm on tank 3, which is my first tank. I patched this one. Welding fuel tanks is dangerous and sketchy work, great way to get blown up if you screw up.

Here's a link to the thread.

Cracked fuel tank #2

How are they cleaning/defueling the tank well enough to solder? I did the soldering on my own tank. I used a pneumatic die grinder on an empty tank and a slow flow of water to avoid sparks as I sanded the area clean of paint which took maybe 10 seconds. Dried the area and heated a thick steel...

forum.ih8mud.com

It is a pretty common problem. Mine wasn't a charcoal canister or pressure issue like some have had. Several of us didn't have that issue but had a tank Crack in a specific spot. There is one tank in that thread that was almost definitely a charcoal cannister issue. It was pretty Imploded looking.

 

[LongDuck]

I had the exact same experience many years ago. Also in PHX, the heating and cooling of a full fuel tank can cause oil-can fractures on the top of the tank that you only notice when it's completely full. Otherwise, you may get a whiff of gasoline and dismiss it as the charcoal filter venting.

Check page 2, specifically; 80 LandCruiser with Fuel Tank Leak... Options? - https://forum.ih8mud.com/threads/80-landcruiser-with-fuel-tank-leak-options.855774/

Also important to note that you'll want to test or replace the Vent Solenoid Valve (*diagrams and part numbers in the link above), as this was the root cause after 2 tank replacements. This valve controls venting of tank pressure to the Charcoal Canister and will also fix your substantial pressure at the fill port. Good luck,

 

[sjpitts]

Thank you for all the replies. I have been ruminating what to do about this, and I am pretty sure that I am going to need to buy a new tank.

But I don't want this to happen again after spending 900 bucks for a new tank, so I want to make sure the excessive pressure problem is fixed first.

After all, this guy went through four (4!) tanks before they figured out the problem.

So it seems like the source of the problem could be:

1) the vacuum control valve 90925-03192
2) the gas filter #1 or check valve 90917-10049
3) the vacuum switching valve 90910-12043
4) clogged lines between any of 1, 2 or 3.
5) the charcoal canister

As I understand it, a failure in any of those can lead to excessive tank pressure and leaky tank.

But after thinking about this a bunch it seems like the most likely source of the problem is that stupid charcoal canister, and maybe more precisely the stupid check valve at the input of the canister that gets clogged up. After all, if that check valve is clogged there is literally nowhere for the gas fumes to expand into. EDIT-- and once the gas expands into the canister, there is vent to the outside from the bottom of the canister that would in theory relieve pressure.

Now, the only reason I know about this stupid check valve is that @LandCruiserPhil pointed out the issue in this thread here. And Mr. Phil recommends removing that check valve to be done with that issue.

That makes perfect sense to me. So I think at a minimum I should rebuild the canister and remove that check valve.

Anyone agree? Disagree?

I guess it would make sense to replace those other three parts above, and make sure that none of the lines are clogged. But again, the real issue seems more likely to be that check valve.

Jared

PS-- does anyone know if the check valve can be removed from the Dorman canister? I am still not 100 percent sure I have all the skills I need to rebuild the canister.

 

[CharlieS]

I would recommend testing the components rather than guessing.

 

[Irish Reiver]

The FSM has good testing procedures for all of these components. Makes sense to follow that and find the source of the issue.

 

[smorkington]

Charcoal canister claims another victim…

 

[DIRTBIKEUSA]

Charcoal canister claims another victim…

So the canister doesn’t vent and the fuel tank ruptures or is the leak from a hose on the tank? Or is it a vent valve the breaks from overfilling?

 

[sjpitts]

So the canister doesn’t vent and the fuel tank ruptures or is the leak from a hose on the tank? Or is it a vent valve the breaks from overfilling?

My guess is that several possible issues and several possible consequences.

1) Canister input clogged (check valve clogged)
-- gas fumes cannot vent from the tank into the canister
-- gas tank pressure builds in extreme heat
--> split goes the gas tank

2) Canister "output" not working (VSV not working, VCV not working, TVV not working, and/or output check valve/filter clogged)
--- gas fumes are never sucked into the engine intake and burned
--- charcoal saturates
--> excessive gas fumes leaking out the bottom of the canister

What I am not sure is if 2) can also lead to tank splitting. The reason I wonder is that there appears to be a path to bleed pressure from the bottom of the canister.

But maybe that clogs too.

And the person I mentioned above that had four tanks split claimed that it was the output check valve/filter that caused his issue.

Jared

 

[sjpitts]

One other thing-- there are actually two check valves at the Charcoal Canister Input.

Looking at the FSM it appears that Check Valve 1 is to let gas fumes from the gas tank into the charcoal canister when there is high pressure, and Check Valve 2 is to let air back into the gas tank when there is a high vacuum in the tank. The same thing the gas cap does.

And it is the check valve 1 (or maybe both) that LC Phil recommends drilling out. And given that it is a clogging of this check valve 1 that possibly leads to splitting a 900 dollar gas tank, I am thinking he is right.

Jared

Edit-- my figure was wrong