[andersta]

Hi.

I've had some troubles with bad performance/ low mpg on my sportage.
Yesterday when I was filling gas I opened the tank cap, and it came a big WOOSH from the cap (just like opening a shaked bottle of coke). It has always been like this, but after filling it, i decided to drive with the tank cap halfway open to allow air entering the tank. and wow what a difference. Suddenly the car became more powerful (still not a racer, but better) I haven't checked the mpg yet, but the engine seems to go smoother.
Is it normal to have a big underpressure in the tank, or is something blocked? Where to look?

thanks for a great forum

 

[chief]

Pressure an vacuum have the same sound .
Check or replace the fuel filler cap. Its a pressure / vacuum cap
check the vent hoses that run parallel to the filler pipe thy can be come clogged or kinked.
There is a fuel tank pressure sensor mounted on the fuel pump mounting flange but if you are have a problem here you should get a check engine light.
Chief