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Discussion Starter · #1 ·
I have a 2012 FJ TT Ed, on the last two gas fill ups I’ve had a considerable amount of fuel spill underneath the vehicle. First time I thought it was my fault for trying to pump as much as possible into the tank. Not the case the second time. I found the rock shield wet and removed it. It appears the gas is coming from the top side front to half way back. There is no physical damage. I’m suspecting. The vent line is loose or O-rings are leaking. Anyone one had a similar experience? Not looking forward to draining and pulling the tank.
 

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There's an access panel under the rear seats. You can access the fuel pump and seals through that hole. Watch the video for the access location. It's kind of cramped, but maybe you can repair things through this hole and save yourself the pain of dropping the whole tank.

 

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There's an access panel under the rear seats. You can access the fuel pump and seals through that hole. Watch the video for the access location. It's kind of cramped, but maybe you can repair things through this hole and save yourself the pain of dropping the whole tank.

Highly unlikely you will be able to do anything except disconnect the electrical connectors from the fuel pump/fuel sender unit. You might be able to see what is leaking, but you’ll still be dropping the tank.
 

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Discussion Starter · #5 ·
Highly unlikely you will be able to do anything except disconnect the electrical connectors from the fuel pump/fuel sender unit. You might be able to see what is leaking, but you’ll still be dropping the tank.
I understand, plan to take a look after Thanksgiving, don’t want to start before in case turns into a real job. BTW I’m getting an occasional check engine light with the code for Evap System “large” leak. Pretty sure that’s not a coincidence.
 

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The toughest line connector to take off is the one I’m pointing at with the pen. That’s because all the other connections are accessible. This one has to be disconnected before you lower the tank because there is no slack.
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Discussion Starter · #8 ·
The toughest line connector to take off is the one I’m pointing at with the pen. That’s because all the other connections are accessible. This one has to be disconnected before you lower the tank because there is no slack. View attachment 1183510 View attachment 1183511 View attachment 1183512
All good information the FJ tank is similar but reversed. I have since pulled the floor access plate and can see where there might be possible leak stains definitely will be draining and dropping the tank this weekend. Is possibly a recall issue?
 

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Please clarify exactly when the fuel leak seems to be occurring.

And what clarify what "considerable amount of fuel spill" means. A few drops, or enough fuel to create a 6" wet spot, or a wet spot substantially larger than 6" diameter?

If leakage occurs only when refueling, when the engine is off, then it would seem most likely that there's a problem with the connection between fuel filler port and the tank itself, or with the fuel tank vent plumbing to the charcoal canister.

If leakage only occurs when the engine is running, then the most likely source is with the pressurized fuel line between tank and engine bay, or in the fuel return line from engine bay to tank.

Before dropping the tank, I'd carefully inspect the charcoal canister and the lines under the vehicle between the fuel tank, canister, and fuel filler port.
 

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Discussion Starter · #10 ·
Please clarify exactly when the fuel leak seems to be occurring.

And what clarify what "considerable amount of fuel spill" means. A few drops, or enough fuel to create a 6" wet spot, or a wet spot substantially larger than 6" diameter?

If leakage occurs only when refueling, when the engine is off, then it would seem most likely that there's a problem with the connection between fuel filler port and the tank itself, or with the fuel tank vent plumbing to the charcoal canister.

If leakage only occurs when the engine is running, then the most likely source is with the pressurized fuel line between tank and engine bay, or in the fuel return line from engine bay to tank.

Before dropping the tank, I'd carefully inspect the charcoal canister and the lines under the vehicle between the fuel tank, canister, and fuel filler port.
Clarifying; how does finishing pumping fuel look down and Feet are surrounded by fuel. Plz read original post fuel is definitely coming from top of tank
 

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Clarifying; how does finishing pumping fuel look down and Feet are surrounded by fuel. Plz read original post fuel is definitely coming from top of tank
Obviously I read your original (and subsequent) posts ,,, that’s what triggered my questions,

Have you visually checked all the hoses and hose clamps between fuel filler port and the tank/evap canister?

If you see leakage only during the filling process, it would seem most likely that the leak is originating where fuel is present during refuelling.

A leak at the fuel pump access cover would tend to leak whenever the tank was full, and fuel was sloshing (cornering, braking, etc.)
 

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Can something like this happen with the charcoal canister or related systems when trying to pump as much fuel into the tank as possible, as stated in the OP?
 

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I'm fairly confident I know what's going on.

The OP is simply overfilling his fuel tank to the point that raw fuel overflows out of the filler neck and drips under the vehicle via the small 'drain hole' located in the rubber apron surrounding the fuel filler neck.

Supporting this conclusion:
1. The pool of raw fuel on the ground under the vehicle ONLY appears during refueling;
2. The OP specifically stated that he was trying to get as much fuel as possible into the fuel tank;
3. The once-per-drive-cycle Evaporative Emissions System self-test would detect even a tiny pinhole anywhere in the fuel system, but the evap self-test must be OK because the CEL has not been trggiered;
4. The large volume of spilled fuel on the ground indicates a significant volume of fuel is not making it into the fuel tank;
5. There is no fuel leakage of ANY kind during regular vehicle operation, only at the time of refueling;
6. The location of the puddle of spilled fuel on the ground coincides with where fuel overflowing from the fuel filler neck would end up ;
7. There is no history of fuel leaks from this area on any model year FJ Cruiser.

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Discussion Starter · #14 ·
I'm fairly confident I know what's going on.

The OP is simply overfilling his fuel tank to the point that raw fuel overflows out of the filler neck and drips under the vehicle via the small 'drain hole' located in the rubber apron surrounding the fuel filler neck.

Supporting this conclusion:
1. The pool of raw fuel on the ground under the vehicle ONLY appears during refueling;
2. The OP specifically stated that he was trying to get as much fuel as possible into the fuel tank;
3. The once-per-drive-cycle Evaporative Emissions System self-test would detect even a tiny pinhole anywhere in the fuel system, but the evap self-test must be OK because the CEL has not been trggiered;
4. The large volume of spilled fuel on the ground indicates a significant volume of fuel is not making it into the fuel tank;
5. There is no fuel leakage of ANY kind during regular vehicle operation, only at the time of refueling;
6. The location of the puddle of spilled fuel on the ground coincides with where fuel overflowing from the fuel filler neck would end up ;
7. There is no history of fuel leaks from this area on any model year FJ Cruiser.

View attachment 1183700
Whoa let’s not get Worked up over this. I do appreciate all comments but I’m not inexperienced driver and can don a head light to perform an inspection. the first time I was trying to over fill the tank and I literally got my feet wetted
After first time I looked at all the oblivious places like the filler neck and the catch box build into the fill vent. As far as the pictured drain for the top of the fill line that would be real easy to see never anything there at top or on ground behind the rest tire. Any way like I said in the original post
1. I have pulled the gravel guard and the leak is definitely come from the top of of the tank This I suspect a leaking gasket or o-ring at one of the ports or the fuel pump. 2. Removing the floor inspection cover was inconclusive and
3. Yes As stated before I have been getting repeated
 

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Discussion Starter · #15 ·
Whoa let’s not get Worked up over this. I do appreciate all comments but I’m not inexperienced driver and can don a head light to perform an inspection. the first time I was trying to over fill the tank and I literally got my feet wetted
After first time I looked at all the oblivious places like the filler neck and the catch box build into the fill vent. As far as the pictured drain for the top of the fill line that would be real easy to see, trust me this is not a case of over filling especially the second time; there has never been any fuel at top of the filler or on ground behind the rear tire. Any way like I said in the original post ( wandering now if it actually posted)?
1. I have pulled the gravel guard and the leak is definitely coming from the top of of the tank fem the middle to near the front. Thus I suspect a leaking gasket or o-ring at one of the ports or the fuel pump. 2. Removing the floor inspection cover was inconclusive mainly due to waiting to pull until after the holiday.
3. Yes, As stated before I have been getting repeated evaporative “large” air leak warnings via my code reader, which is annunciated via the check engine light.
4. Yes, in my ownership of many vehicles I never had a leaking fuel tank and I’m also skeptical that the actual tank is leaking. Mainly because There is no physical damage to the tank.

Problem now is how to drain the tank before pulling.
I’ve tried inserting a 3/8” tube and it gets stopped at approx 5’, just before entering the tank in a minute I’ll a 1/4” tube. I’m thinking, like my F150 there is a strainer to prevent siphoning hopefully not. I’ve thought about hot wiring the fuel pump as a last resort.

Any thing you guys think I’m missing?

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Discussion Starter · #16 ·
1/4” line could not penetrate the tank either, will pull a vent line at floor access and pump from there. Point being to reduce the risk spilling fuel while lowering a full gas tank.
BTW first spill was probably a gallon second was a pint to a quart. Real problem is the check engine light.
 

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1/4” line could not penetrate the tank either, will pull a vent line at floor access and pump from there. Point being to reduce the risk spilling fuel while lowering a full gas tank.
BTW first spill was probably a gallon second was a pint to a quart. Real problem is the check engine light.
I seems like you've decided there MUST be a leak at the top of the tank, but you're completely ignoring all of the evidence that indicates that is not the case, and are fixated on dropping the tank.

So, explain to me how and why:
1. The leak ONLY occurs when you are refueling, and NEVER when you are driving? How can there be ounces of raw fuel running out on the ground when refueling and the vehicle is stationary, and yet not a drop when driving (cornering, braking, and accelerating), with fuel sloshing wildly in the tank? Doesn't this seem a bit odd? If your theory about a defective O-ring at the fuel pump cover is valid, why would fuel pour out only when the vehicle is not moving, and the fuel pump is not running?

2. The extremely sensitive Evaporative Emissions System self-test, which runs every night and checks for the most minute leak anywhere in the fuel tank, charcoal canister, and fuel fill and vent lines, has not detected this massive fuel leak? (The Check Engine light is not on, correct?)

What does the physical evidence point to?
 

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Discussion Starter · #18 ·
I seems like you've decided there MUST be a leak at the top of the tank, but you're completely ignoring all of the evidence that indicates that is not the case, and are fixated on dropping the tank.

So, explain to me how and why:
1. The leak ONLY occurs when you are refueling, and NEVER when you are driving? How can there be ounces of raw fuel running out on the ground when refueling and the vehicle is stationary, and yet not a drop when driving (cornering, braking, and accelerating), with fuel sloshing wildly in the tank? Doesn't this seem a bit odd? If your theory about a defective O-ring at the fuel pump cover is valid, why would fuel pour out only when the vehicle is not moving, and the fuel pump is not running?

2. The extremely sensitive Evaporative Emissions System self-test, which runs every night and checks for the most minute leak anywhere in the fuel tank, charcoal canister, and fuel fill and vent lines, has not detected this massive fuel leak? (The Check Engine light is not on, correct?)

What does the physical evidence point to?
FJtesty, Thanks for the concern, The three things that I had failed to clarify are: 1) that after the second incident I pulled the rock shield and visually confirmed the fuel coming from the top of the tank, 2) the Evaporative Emission self test IS detecting a “large” leak in the system, clearing the fault codes results in the same two code returning after a
Few miles or days as you said it should, and 3) I do smell fuel while driving the vehicle and in my garage. I assume, Fuel only hits the ground when refueling because that’s the only time the fuel level is consistently above the leak.

It may take a Few days but I’ll close this thread with pictures of the problem once I find it. Thanks to all for the good information presented here. To FJ test, Until then please refrain from committing unless you have something constructive to say. The point of the forum is to help people with FJs get down the road not criticizing and belittling them.
 

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If you can coordinate this with target tank drop day, try and run it down to at least triggering the reserve fuel warning ⚠ light. If there is 3-4 gallons in there, it’s manageable. You’ll need to get it up on jackstands to have enough room to wheel the floor jack and tank from underneath the FJ. Good luck, it’s not too bad.
 

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FJtesty, Thanks for the concern, The three things that I had failed to clarify are: 1) that after the second incident I pulled the rock shield and visually confirmed the fuel coming from the top of the tank, 2) the Evaporative Emission self test IS detecting a “large” leak in the system, clearing the fault codes results in the same two code returning after a
Few miles or days as you said it should, and 3) I do smell fuel while driving the vehicle and in my garage. I assume, Fuel only hits the ground when refueling because that’s the only time the fuel level is consistently above the leak.

It may take a Few days but I’ll close this thread with pictures of the problem once I find it. Thanks to all for the good information presented here. To FJ test, Until then please refrain from committing unless you have something constructive to say. The point of the forum is to help people with FJs get down the road not criticizing and belittling them.
H16sailor -

I think you have misconstrued my comments here. Part of my day job consists of failure analysis work with complex electro-mechanical systems, and I find it interesting to try to determine what's going on when forum members describe problems they have encountered with their vehicles.

Obviously, a crucial element is that the person experiencing the 'problem' provide an accurate and thorough description of what they are observing.

Not even mentioning that the CEL was on, and that you had interrogated the OBD system and found a code indicating a gross leak in the evaporative emissions system, painted a very incomplete picture of what was actually going on.

Not sure why you would consider my well-intentioned attempt at problem solving (unfortunately based on incomplete description of the problem) as 'criticism' or 'belittling', as it was an honest attempt to help solve your problem.

Toyota's implementation of the OBDII system is very comprehensive, and clearly stating if the CEL is illuminated and what OBD fault codes may have triggered the CEL immediately helps anyone interested in the thread understand what may be going on.

By all means take some photos of what you find when you drop the tank and post them here. A fuel leak of this magnitude from this area is very unusual, unless at some point someone has attempted to perform some kind of repair work and didn't quite get it right.

Do you know if the fuel pump has ever been replaced, or the tank dropped for any other reason?
 
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