I installed subwoofers in my trunk and I was playing it load and my gas cap pop off and my gas gauge is going up when I crank up the car and then it goes to half way and want move even if I feel it up what is the problem

No

Well, was it doing this before you installed the speakers?

No one morning was driving to work and I had my music turned up and I started smelling gas so I check my gas cap was off and my gas gauge was not working right and I have been getting different answers I just want to get it fix and my voltage meter is acking up to all of this was messing up at the same time while im sitting at a light my meter keep going up and down and my car ack like it's going to cut off

For technical assistance for any audio system problem and information on wiring size and amperage needed to drive your 1200 watt amplifier plus the speaker RMS requirements .. Google Crutchfields .. You are still overloading the vehicle's electrical system .. Especially at idle! .. Good luck!

Thank you so is that the problem for the gas gauge to ?

It a very good possibly since low voltage will cause all kinds of problems plus it just started doing this after your add on.... They got free tech assistance!

Where can I go it tested for free in Oklahoma city ok?

Don't think anyone is going to do hands-on testing for free.. Crutchfields offers free tech advice over the internet... You can always unhook the amp!

the alternator ain't gonna really help him!there are other ways to hook all that stuff up with capacitors and another battery in the trunk or just capacitors.he's just either got to get the right things or the right person because 1200 watts on a 12 volt DC system is pulling 100 amps! that only leaves 30 to run the vehicle stuff..that's why all the crazy stuff is going on,and it will stall,and will burn that 130 amp alternator up sooner than later.i have went through all this(not with stereo amps,but other type amps)for what we call DOG FIGHTING or SHOOT OUTS>(CB RADIO SLANG)and i ain't talking bout no 4 watts talking to my neighbor a mile down the road or like truck drivers either! more later...

I've been down that road too! .. Key the mic and turn dusk to dawn lights off around the neighborhood! .. There is a ton of info on how to correctly wire up a custom audio system but I ain't going to get into that.. I've done it before for some kids but don't fool with it anymore.. Extra batteries will surely help.. So will correct wire size and type .. BIG difference in current and voltage.. Takes too long to tell that story .. Way too long for me to get into it that is! .. Nowadays i just tell em I don't know a thing about it.. Plus there are laws against loud music in certain places .. Just as it should be!

1200watts and I upgrade my alternator to 130 amps police package

get on Ebay and buy you one of those 200 AMP LEECE NEVILLE ALTERNATORS!! a good one is $2000.00!!! use it just for your system,although you will have to modify some things!