Odyssey Gas Tank Leaks only when 100% Full

If anyone can help here appreciated. I have a 1999 Odyssey
I had an accident 3 weeks ago where my car rolled down my driveway (with no one in it) and ran over some landscaping rocks. The rocks crushed my gas
tank.
They replaced the gas tank (and a few other minor things) - but now when I fill up the tank completely - there is a smell of fuel in the car and there is a small amount of fuel dripping from somewhere out of the top of the tank and dripping on the garage floor. I can't see where its coming from but obviously from the top of the tank somewhere. Again - this problem only occurs when the tank is 100% full. If 95 % full - no leak. The small amount of gas that leaks stops after the car has been turned off for 20 minutes (it does not continue to leak all night or anything like that).
Obviously - the van goes right back Monday morning - but I just wanted to know - if not the tank - what else at the top of the tank holds fuel and could be leaking for a short time after the Odyssey is turned off.
All help appreciated
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I might also add - it seems to me that to to see what part is leaking - you would have to take the tank down. But with the tank off (and emptied) - it may be difficult to see where the leak was coming from if nothing is obvious.

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A leak like this is often the overflow tube that runs alongside the filler neck. A clamp might be loose or missing, or the tube may be cracked where it comes out of the tank.
To investigate thoroughly, you'd need to have the car up on a hoist, and have a strong light. If this is a collision repaired car, ANYthing could be damaged. Anything from broken tank seam to a split hose to a broken pipe to missing clamps.
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TeGGeR

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There is an access panel to the fuel pump under the carpet and second row seats. Perhaps you can see something from there. There are a ton of pipes and hoses in the top of the tank and it will have to be lowered to get to most of them. They should be able to find the leak with the tank empty with a smoke test or pressure test.

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Can you tell me more specifically where this access panel to the fuel pump is? Under the driver-side 2nd row seat? Does the carpeting have to be cut to get at it (or does it pill away). Thanks

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The second row seats have to be removed and the carpet removed. This doesn't give access to all pipes going in the tank as there are several. Your best option is to take it back to whoever replaced the tank and have them fix it. It could also be a crack in the plastic tank.

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obvious trouble point.
Troubleshooting is pretty much the same as testing. The cap is replaced with a pressure adapter and the tank is pressurized to a pound or two - if it doesn't hold, it's a matter of listening/feeling for the leak. I've done it before in our old Volvo with an adapter to a bicycle pump, and it's amazing how much hiss there is from a very small pressure.
Mike
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Mensa wrote:

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I would suggest to keep the van out of the garage until it is fixed. It is not worth a chance for a fire hazard like that in your home. I hope the garage is not attached to the house. Be careful anything can ignite and cause fire or explosion.

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Traveller wrote:

exactly! and doubly especially so if theres a gas fired water heater in the garage the van is in.
i fried the engine bay of an 81 mazda 626 many years ago because it had a carb leak and i pushed it into the garage to work on it. once the water heater 15 feet away kicked in, the fumes from the small puddle on the ground instantanously combusted.
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