Fuel tank IMPLODE issue: which valve is stuck bad?

I searched the topic and there's only one that mentioned this.
https://www.ferrarichat.com/forum/threads/fuel-gauge-reading.473726/#post-143651531

after
1. test driving this car for hundreds of miles chasing for reason why the BRAND NEW gas cap is sucking in air through the 6 holes on it and causing Terrible noise.
2. thinking why the body has no evidence of any collision damage and the gas tanks are bent or otherwise having a damaged shape
3. having a p0440 code.
4. fuel indicator isn't showing what it should be showing.

I finally realized that it is something that was stuck in the fuel loop that caused the vacuum inside the tank so big that the tank imploded!

now, could somebody point me which valve is faulty to caused this?
is it one of the following?
1. on/off valve around the charcoal canister
2. two small valves that allow vapor going back to air intake
3. big "multifunctional valve" (as called by ferrari) collecting fuel vapor
4. roll-over valves?

or is it something else completely?

 

yes, It literally collapse. I'll take a few pics later.

I don't believe it either, at first! At first I thought somebody must be replacing good tanks with bad ones and sold it, but after I noticed all factory plastic zip ties are intact, I am puzzled. ( you need to remove engine to get those 2 tanks replaced, to remove engine, you need to clip those factory zip ties).. So yea, conclusion is, there's no accident happened to the car and the fuel tanks are original to the car!

secondly, I had this HUGE noise coming from the gas door and i thought it was something inside of the quarter panel. Wrong after I put my finger to the gas cap and found the HUGE VACUUM that sucks my finger to the cap through the 6 holes in the cap and the noise stops. ( it is a brand new cap from my other Modena)

The car runs fine! I only realized this after all these symptoms put together ( intermittent, not always but "once on it is always on" huge noise from gas cap, collapsed tank, p0440, fuel indicator on dash erratic, )

My English maybe bad, but by implode I mean collapse.

 

check which valves are stuck open as a start? They are supposed to be stuck open or supposed to be closed?

by "front part of the engine air intake", you mean next/behind to the firewall bulkhead?

 

here's a few pics of the RH tank, LH is similar but deformed differently
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Read your explanation 3 times, finally get it with the help of the evap diagram.

That was just a brilliant idea. Let me get a rest and replace these 2 small valves with my other Modena's.

 

1:30am----3:45pm here now. done replacing the 2 purge valves. One of them is open when I blew it. The other one doesn't let any air thru.

 

there are a lot of cases outside the ferrari world, like volskwagon and fords but their tanks are usually not aluminum.

 

it looks like , in my case, it is not a plugged vent system, rather a singular cause of intake vacuum acting on the gas tank thru a faulty valve. I'll drive 100 miles and see if cel came back. I bet no.

 

Please be advised that this is a euro version 360 modena, not a US version. The anti-evap system of the US car is similar but parts are located on different locations and some parts are a little different as well, though they may serve the same function.

Analysis and account of events.

1. Replaced the charcoal canister with a known good one ( installed a new one on another modena and drove only 5000 miles), make sure its not plugged.
2. TEST 1 in green font in the picture. This valve on top of the charcoal canister is controlled by a 12v signal. I remove the valve and blow through it without applying 12v, air goes through. Applied 12v, air won't let through. So this is a good valve.
3. TEST 2 in green font in the picture. This is not a signal controlled valve. I only removed the bottom hose from the valve and blow it, and it let air though. When upside down, the shut-off valve on top of this thing works, so no air through. So this is good.
4. TEST 3 in green font in the picture. (kudos to vrsurgeon). These 2 small valves are voltage controlled valves. I removed these 2 small valves, and blow them without applying voltage. One of them isn't letting air though, which is good. The other one is letting air though, which is bad. I don't even have to apply voltage for the test because these 2 valves are identical.

So that means one of the small valves is bad.

About how the fuel tank got vacuum: the intake manifold obvious is the source of the huge vacuum, when the small valve in TEST 3 fails, it let air through. Look at those green arrows, you can see that the vacuum find its way, through the charcoal canister, to the fuel tank! And that basically is what happened.

When the fuel tank has a pressure problem, it will give you a CEL, in my case p0440.

So please do not ignore your evap related cel unless you want your $5000 fuel tank to collapse like mine, although it is a very small odd.

I maybe lucky that I don't smell any fuel , but i'll do a thorough check if the fuel tanks have any tiny leaks. If no leaks, i'll just leave them as is.

Thank you for reading.


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these are the small valves in TEST 3. Image Unavailable, Please Login

 

Now I am confused about another thing.
The vacuum in the fuel tank only happens after I drive for a while. It has no vacuum(not that it didn't build up yet) when it starts, cold or warm.
I can only surmise that the valve in TEST 3 is open when car just starts hence the sucking action is diluted to the general atmosphere. The vacuum in fuel tank only starts to build when the valve in TEST 3 closes.

Is that the case?

 

this one is 2002. If you have a US car, no matter what year it is, these 2 valves are on the driver side. Pic shown is the passenger side(RH side).

 

first, your 99 euro car shouldn't have the on/off valve above the charcoal canister. Euro cars has 2 versions of canisters, mine is the later version with 4 holes. Yours must be a 3-hole version

I think the valve #12 lines enters the canister with the same function. Reason: i held my 4-hole version canister in my hand (removed from car). Using my mouth to blow the hole from line coming to valve 12-1 and cover all other holes, except the hole from line coming to valve 12-2, it let air through

so they are