Check fuel cap

[Mireau's LS]

Hello all, would like to start by saying I've lurked here for quite some time now and love the site. I've come from a dsm and a rocket forum but have switched to an LS and love every minute of it.
My question is this, in the message center in the dash, a "check fuel cap" keeps coming up. This happens whenver I start the car and if I reset it, the message will randomly pop up again. This happens several times a trip.

From my searching I've found the drive around, take sharp corners, go fast then slow trick to fool the ecu into fixing this. This worked once but now the message won't go away. Yes I have checked the fuel cap. I'm thinking it could be a vacum line.
Please help, thanks in advance.

 

[joegr]

Actually, it could be a large number of things. There are several hoses involved, several gas tank seals, a couple of solenoid valves, and a carbon canister assembly all involved in the fuel tank system. A leak anywhere from any of this would cause your warning message.

The section in the factory manual is probably not going to help much since you probably don't have a smoke machine, but here it is.
http://deneau.info/ls/s6x~us~en~file=s6x3d004.htm~gen~ref.htm

There's some more info here.
http://deneau.info/ls/s6x~us~en~file=s6xs3d0l.htm~gen~ref.htm

 

[Mireau's LS]

Fantastic. You are right, I do not have a smoke machine. Would you have any ideas on things I could check before I bite the bullet and bring it in? And would this cause the car to have less then normal mpg? I get 15ish in town, I used to get 26ish on the highway but since the message I only get around 17ish on the highway. Thanks again.

 

[Alax7]

17 on the highway?!!!!!!!! That is low. Unless you're going like 90 or 100. Going 65 I get 25+ mpg I think. I usually drive 70 which is around 22mpg

 

[Mireau's LS]

Yeah, I used to get 26 or so on the highway, doing 65 -70mph. I hate going to the gas station even more now!

 

[Lincoln Jealous]

have you checked your gas cap? sometimes the seal wears down and doesnt hold the pressure in the tank

 

[Lincoln Jealous]

17 on the highway?!!!!!!!! That is low. Unless you're going like 90 or 100. Going 65 I get 25+ mpg I think. I usually drive 70 which is around 22mpg

the faster i go the better mpgs i get

 

[rainjacks]

the faster i go the better mpgs i get

Cool, as you approach the speed of light your mileage should approach infinity. You are driving a time machine!

 

[owlman]

Yes I have checked the fuel cap.

have you checked your gas cap?

 

[Lincoln Jealous]

degas or overflow

fuel or gas

potato potato

 

[Lincoln Jealous]

Cool, as you approach the speed of light your mileage should approach infinity. You are driving a time machine!

i tried to tell ya!

 

[Mireau's LS]

I did check the fuel/gas cap for wear as well and nothing. The car is an 05 with 24,xxx on the clock so wear and tear is a minimum.