Change the fuel pump gas gauge was working before after changing the fuel pump gauge stop working

I'm not 100% clear on exactly what isn't working from your question other than now the car is starting and dying after changing the fuel pump. In that case it's possible you've oppositely attached the positive and negative wires to the fuel pump. Hope this might solve part of your problems.

check your fuel pump relay. if not that, then it's your fuel pump. the gas gauge is in the fuel pump, so if your fuel pump stopped working, your gas gauge won't work

In most cases, the reason why a gas gauge might stop working is because the sending unit located insider the fuel tank may have worn out. In some cases, this may require you to replace the fuel pump as well, because a lot of times they come with the fuel level sending unit attached. Otherwise, if your car is indeed fuel-injected and you are planning on dropping the fuel tank and changing the sending unit, I would also recommend changing the fuel pump as well, for good measure. I hope this helps! :)

As the fuel pump and gauge sender unit are in close proximity to each other I would be checking a wire connection is not loose or an earth wire left off at the tank

If the trouble with the gauge started after you worked on it then you likely damaged or created a restriction to the movement of the sending unit. You will have to remove the tank and double-check your work.

You might have bent the gauge pin when changing the pump there is a lever that is easly bent you might need to take it back out of ther tank and fix..

Hey man if you already changed out the relay i would try changing your fuel pump and sending unit that should stop both of your problems.

Gas gauge has nothing to do with fuel pump. possible causes:

1. Low fuel in tank, get some more fuel
2. Rat chewed the fuel gauge wire or its socket is loose
3. gauge itself is faulty

this problem is caused by a defective gas gage sending unit, the sending unit is located inside the gas tank and to replace it u must remove the fuel tank from the car.

the sending unit is a variable resistor(potientiometer ) on the fuel pump
its probly bad it requiers a couple confirmation tests prier to dropping your gas tank and changing the pump but I got my money on that sending unit 97% of the time new fuel pump will fix it you coul change just the sending unit but you still have to pay almost as much and its the same job smartest thing too do is change the whole thing