James Dean

Does every else’s 2nd gen 4Runner develop allot of pressure in the tank. When I go to fill up, I have to let the air out slowly. It literally will blow the cap off if you remove it fast (not like a gun, but enough to make you drop it). I know all tanks have it, but I've had plenty of rides in my life and nothing like this. Does this sound like a problem or is it normal?

nate V

Yeah it is a prob

I would check your Charcoal Canister and see is its working properly.
Its the big cylinder on you pass side under the hood. Might need to replace that. Or your line might be clogged.
The Charcoal Canister receives the tank pressure vapors and incorporates it into your vacuum system.

dirtyXplorer

I have this same problem, even if I fill up on half. Mine almost sounds like suction but I am not sure. Is there any way to test the charcoal canister? Is there any bad side effects?

longhungsilver

there should be a bit of pressure (if the system hasnt just depressurized recently)...if its enough pressure to blow the cap out of your hand id say theres a definete EVAP problem. It should throw a code eventually tho i would think

Tacoma750

Mine does it to...Sounlds like someone let the air out of an air compressor when i take the gas cap off lol

8yota9

i second the air compresor lol

fastkevman

My '93 does it and seems to run very well, so I'm not worried about it.

Bigblock

All 3 of mine do it!

Green93

Mine does the vacuum thing too. The engine needs this vacuum to function properly. This is why you get a check engine light when the girlfriend doesn't turn the cap on tight enough. I always tell her...make it click a few times. She learned now since she had to take time out of shopping to go sit at the dealer while they tested it and reset the light.

If it blows out when you take the cap off then something is wrong somewhere.

Jason

nate V

Not sure if you can check the Charcoal Canister or how you do it but I would recommend that you look in haynes or chiltons manual...
I know that the newer cars and trucks run at a much higher tank pressure than the old ones do with early efi. So if it leeks it should throw a code depending on the year.

89934runr

If your canister is jacked, I have one for ya. Your TVV cycles vacuum to the tank in order to burn the fumes- it might not be cycling, or your canister is blocked. Either that, or one of the check valves in the canister is blocked. You can blow it out using mid-pressure air (no more than 45psi). DO NOT use solvent in there- it will kill the charcoal inside.

What I'm getting to is that I THINK your tank isn't venting, so like any enclosed gasoline, it develops pressure- VERY dangerous is your in a dry part of the country (you'll wind up on the news / Youtube as 'that guy').

Easy to check!