Fuel Lid Tight or Loose?
 

I spent a few mins using the search function to try and find an answer, but no success!

I have always wondered about the fuel cap being tightened or left not air tight. I always leave it, loosing-ish, not air tight, my logic is that when the fuel is being drawn from the tank, if air tight there would be pressure that wont allow as much fuel to be sucked out.

That is just my logic, but i have no idea :(
What do you do and why? Or is there a way its suppose to be for a legit reason?

Thanks for the help!

Fuel tanks don't usually breath through the cap. In fact you may even set off a cel, or so I have been lead to believe, if the cap is not tight?

Yeah, if you leave the cap loose for to long it WILL throw a CEL

I've always heard the same thing. Never confirmed it though...

The fuel cap needs to be tight! How do you know if it's tight? Twist until it clicks at you.

If you don't tighten your fuel cap it might cause issues with the evaporative emissions controls as the tank is currently permanently vented to the atmosphere and that can trigger a check engine light.

What others have said before, and if I remember correctly the newer cars will actually have a fuel pressure sensor in the tank, I assume for emission purposes. So I would imagine the cap has to be tight to help keep a consistent pressure in the tank.

Hope this helps :)
Thanks,
Rick

Weird. Mine doesn't click. Don't get me wrong, I turn that thing until I can't turn it any further, but I don't get any clicks.

That's weird...not even a click?? Could be a faulty cap...bring it back to the dealer...

My BRZ clicks just once and it doesn't let you tighten any further after that click.

Not a click, not a peep, nothing.

Weird, even my 01 Tahoe will keep clicking after a point if I keep turning it

Yeah...that doesn't sound right. FR-S is the same, it clicks once and then won't turn any more.

Nice. I'll have it looked at when I take it in for an oil change.

Ok, needless to say, i will will be tightening that cap when i get home :) THANKS EVERYONE!

My ex didn't tighten the cap on her XB and it definately threw a CEL.

How long did it take? Does it take some miles before it came on or was it right away?

Between 15 and 30 miles. Enough for the pressure in the tank to create a vacuum from the displaced gas.

Cool...kinda what I figured...thanks for the info! :happy0180:

That's backward, my brain was fried from studying. It is 15-30 but with the cap on the tank pressurizes. If the cap is off, it can't and the cel goes on.

An easy answer is read the owners manual. Turn it till it clicks and release.