Ok so i havent bothered with this since i always was thinking that this is normal but no other car that i know of does it, everytime i open my gas cap i get a shhhhh sound out of the tank, i know its gas preassure being let out but why is my tank under so much preassure then ? I got the canister in the engine bay and its all connected tho the canister itself looks like the PO replace it with a junkjard one since it has all the typical junkyard writings all over it. So is this normal on thirdgen TBIs ? The other day i went to start the car and it died twice , fuel was not getting to it, and i could hear bubling inside my fuel tank or atleast thats what i think it was but it did sounded like someone blowing bubles like when u blow into a glass of water with a straw, the third time it cranked right up and has been ok ever since, can the gas cap be causing this, i think its a replacement since its not attached to the car anyways it just comes completely out and does the cracks when i screw it in all the way so the cap is a direct replacement if it was ever replaced.

 

Sounds like you are building a vacuum in your gas tank. The shhh could actually be air rushing in. I had something similar when in my TPI a check valve stopped working. I would get the shhhh noise or if i drove it from full tank to full empty i'd get a shhhh and then a light thunk from the gas tank sheet metal popping back into place.

 

You have a vent valve coming off of your tank connected to a hose about 6-12 inches in length. Could be plugged...

 

normal ........

 

yup.

my car never did this until 2 years ago when I had to pass smog and found a crack in my filler neck area. reparied the crack and then it hissed afterwards when i removed my gas cap after driving. before this i always smelled fuel but never knew from where.

 

When it DOESN'T "shhhh" is when you need to start looking into it. Means something is leaking somewhere.

Could just be a bad cap.

 

thx for the answers guys , i guess its normal then cuz my car does the shhhh when i open the gas cap so i guess all is normal, now what it did the other day was weird that bubling inside the tank got me worried it did it when the pump was priming but i didnt hear the usual sound the pump makes when it primes instead i heard that bubling lol, was it running in the wrong direction and making fuel go the other way out the feed like ?

 

Every thirdgen I ever had built the vacuum in the tank like that from day one. As said before, that is normal.