My cars fuel system seems to have a problem, the check engine light came on, the loose fuel cap light has stayed on (caps been replaced) light continues. It revs high like going to 4 on the tach when I’m only going 35 so I try to accelerate slowly, when passing that’s a problem, I suspect it’s in the vacuum system. One mechanic told me it’s nothing another, said he’d have to do a smoke test to discover the problem. It leaks gas if I only go a click over full, and the gas mileage isn’t even the 25 mpg? Just wondering what it might be?
The loose fuel cap light illuminating is most commonly caused by, well, a loose or defective fuel cap, but it could be caused by a leak anywhere in the fuel tank - fill and vent hose - evap system.
You say it leaks gas when you fill it beyond the first click. Overfilling it can cause havoc with the evap system.
You need to get the codes read to determine why the check engine light is on. Many auto parts stores will do this for free. Report back. I suspect you have more than one problem.