Gas Shooting back out of cap (when filling)

[m5racer]

Alright so i went to the gasstation yesterday. My gas tank has been fucked for a while now, it only lets me put like $2 in a t a time before it clicks, then i need to take out the pump, let the gas go into the tank and the go back and continue filling. It s been like this for about 6 months now. YEsterday when i was filling up it would not longer allow me to but $2 and let it go down but instead, everytime i took the pump out to let it get air get it the gas would violently shoot out of the tank and it would go all over the side of my car and on the floor. by the time i hit 20buxs there was a huge puddle on the floor from all the gas comming abck out of the part where you fill it.

Im getting a buddy to look at it today, what do i need to fix this problem beucase i cant stand it anymore, and i cant even fill gas beucase half of it ends up on the floor

Thanks,

Anthony

[zrowcool]

maybe your using cheap gas or too low of an octane and your car's spittin it back out cause it deserves better.

on a more serious note, i would think its the little carbon canister since thats what relieves pressure inside the tank when you give it gas. i think its accesible through the trunk by the vacuum pump. that would be my best guess.

[m5racer]

its not cheep gas, i use sunoco 94 only, and go to diffrent locations all the time. its the car, not the gas or pumps

[njm23]

it is your charcoal canister it isnt releasing the pressure.

[Bic-Ball]

make sure you clean the gas off the car

[m5racer]

ya it rained pretty heavily yesterday + i hosed it down with some water at the gas station. man this is such a pain in the ass

[Nebone]

and i cant even fill gas beucase half of it ends up on the floor

So it costs you $100 to fill your tank and takes half hour to do it? I'd be pissed too...

Charcoal canister will pay itself back in no time that way.

[Mike@PureMS]

As others have said it's your evaporative system that's the problem. The EVAP system allows the tank to vent, and keeps the air pressure inside the tank low. Part of the evap system is the charcoal canister and the evap purge valve. Have these guys inspected, something's not right with them.

[urban96]

could there also be some kind of blockage in the filler tube?

[biketsai]

Need a new charcoal filter.

[widgget]

My B6 just started doing this last night.

anyone have a part number by chance? what do they cost?

and last..... where is the thing? i don't know where the vacuum pump is. is it under the fuel pump cover?

[zrowcool]

on the b5 its in the trunk, on the right behind the panel. The vacuum pump is on the floor and the charcoal canister is more forward towards the filler neck. Not sure if the b6 location is the same but it should be since the filler neck is on the same side.

[turboquattro]

I have this same problem except i can only fill about 70 cents at a time!! What ended up being the problem? i go to school in Oregon, so i cant fill up my car and they usually refuse to keep filling after about 10 bucks!! Another thing i noticed is when i unscrew the cap there is absolutely no air pressure released, but when i pull the actual pump out of the car i hear pressure!! i dont even know what the deal is.

[Toyotatech]

First the pump nozzle swings open the cover in the fuel filler tube filling hole. The cover pushes a venting switch which allows the fumes(pressure) to flow down down the vent tube into the carbon canister. Use your finger to push the cover all the way open to feel the switch opening. If the venting switch is bad you are in trouble because the only way to replace it is to replace the tank.

So as you fill the tank the fumes flow through the venting tube to the charcoal canister mounted under the round plastic cover under the spare tire accessed from under the car. The carbon granules absorb the raw fuel fumes and clean air is vented out the canister through the LDP pump. The LDP(leak detection pump) turns into a vent when the car is turned off. That is the little filter that you see under the left rear wheel well liner. The fumes from the granules are pulled back into the engine by vacuum (regulated by the N80 valve) to be burned off when you start the engine. So the problem occurs when your tank doesn't vent properly as you fill the tank. The pressure build is what causes the gas to quit going in and the nozzle to shut off. The problem could be a clogged up charcoal canister or a non-functioning LDP.

The easiest way to determine if you have a blocked canister is to remove the large tank to canister hose on the passenger side of the canister after you remove the circular plate covering it. Then go fill your car. If the tank fills easily then most likely the canister is blocked. You can also have a defective LDP pump which will not vent. To determine if that is the problem you need to reconnect the large vent hose just removed, drive the car until fuel is low, and remove the small vent hose on the canister driver's side(this is not the small hose along side the large hose on the passenger side). The large hose is an easy disconnect(push or pull ring, pull out hose). This small hose needs to have the clamp cut off and replaced with a normal hose clamp when done testing. If you can't fill the tank this time with the small hose off, then the canister is defective, if you can fill the tank with the small hose off then the LDP is bad. Change the canister first as this is the most likely problem.

Right after start up (and at other intervals as controlled by the ECU) the ECU closes the evap purge valve (N80) and runs the leak detection pump (LDP) to slightly pressurizes the fuel tank. The pressure bleed down rate is monitored and if it drops too fast a CEL will result. For example a loose gas cap. If everything is OK the leak detection pump turns off and the N80 begins it's duty cycle to purge the tank fumes. So if you try to fill your tank in the first few minutes after start up you may find that the system is still pressurized from the leak detection diagnostic cycle and you will have difficulty getting the tank to fill.

I'm not sure if your car has the leak detection pump though.

[fernando]

it is your charcoal canister it isnt releasing the pressure.

before you go out and start looking for a new canister make sure that your tank breather is not block....it will be under the car along the filler neck.....