What is the question? There has to be more to the stories. Why was a new gas cap needed? Sometimes auto parts stores have an exact match for your car, but they can't stock hundreds of different caps, so you'll typically find a universal replacement that works on your car and many other models. Most will click and ratchet when you try to over-tighten them, and that prevents them from getting too tight. If yours doesn't have that, just don't tighten it so much when you put it on. Otherwise you'll have to get the right cap from the dealer or a salvage yard.
The float in the gas tank, for the gauge, is likely hung up on something. That isn't related to the gas cap. It may let go by itself and start working correctly again, but if it does, that usually happens when the level is low in the tank and you drive on bumpy roads.
As for the battery, there is almost no chance you will ever get a new one that is identical to the old one, even from the dealer. The manufacturer bought a special run of batteries, perhaps tens of thousands, from the supplier, that were built to the most inexpensive specifications as possible that would still get the job done. The replacements will almost always be better, but they will look different. The size and shape of the battery has nothing to do with it being drained if you leave something turned on. You said you "can't leave anything going". That is true of every battery ever produced, and it's true about every car. If you leave anything turned on that uses electricity, of course it is going to run the battery down. The head lights will kill the battery in less than two hours. The radio alone might last six hours, but the problem is to play the radio you have to turn the ignition switch on, and that turns on a whole pile of computers that are all trying to run their systems too.
This is not a paid service. The site owners allow you to ask for help for free, and I like it that way. Thanks to a major house fire last year, I drive 21 miles round trip almost every night to sit in the library parking lot and use their wireless internet to see if I can help someone. Those who are grateful and able may make a small donation, which is appreciated, but that is not expected. What I DO expect after putting in all this time is for you to be appreciative. I just got a snotty reply because the person typed a half a sentence with no punctuation, no details, no clue, no symptoms, and expected an answer.
You can reply anytime but I won't respond until I see it, which might be a day later. Don't worry about a donation. Most people don't make a donation, then some of them think we won't reply. In fact, the very few posts that don't get a reply are those that haven't included enough detail for us to come up with a valid answer, or it's for a car none of us are familiar with. Each of us are only here a few hours per day, so it could take a while for a post to be seen by the one person qualified to answer.
Tuesday, June 9th, 2015 AT 11:12 PM