1991 Cutlass Will Not Start!

Drove the car for 45 min. or so, and it started acting like it was out of gas (the gauge read 1/2 full), and it stalled out. It turned over but wouldn't start.
Checked to see if it was getting gas. Pumped some gas out to check gas lines. It pumped out fine except it was over 3/4 water, it didn't have an odor and it beaded up.
Pumped at least 5 gal of the liquid out before it started smelling like gas. Gauge reads 1/2 full.
Put 5 gal of gas in it and got it to start and drove it home. It ran terrible.
Next day it wouldn't start so I put some "Heat" water evaporator and 108 octane boost in the tank. Rocked the car to mix it up a bit, but didnt hear it slosh around.
I think someone drained my tank. Gauge reads 1/2 full.
Put another 5 gal of gas in it. Still won't start. Gauge still reads 1/2 full.
Replaced the fuel filter & (bought a locking gas cap).
Car turns over and Still will not Start!
PLEASE HELP ME!

Hi. Clean fuel will certainly help but if it's even pretty good, it should still start. What motor is in the car - the 3.1 V6? I would check to make sure that you have fuel pressure at the fuel rail. If you look at the Plenium (the part that says 3.1 multi port on it - top of the engine), there is a valve to the right of that with a silver cap on it. You can unscrew the cap and press on the valve with a small screw driver to see if fuel comes out. If fuel doesn't spray out of there then you're not getting fuel to the injectors. You should then check for a bad fuel pump or filter but you said that you replaced the filter. By the way, put a towel over the valve while checking this so that you don't get sprayed it in the face when doing that. I think it's possible for you to purge the lines by taking them off at the fuel rail. You could then put a piece of hose over the fuel line and run it to a container and turn the key on. The fuel should flow through the lines into the container. Just a thought.

Did you get a check engine light when driving it home when it was running rough? You can easily get the codes out of that computer and post them here for someone to identify them. If the fuel is fine then the ignition is suspect. This car has a crank sensor, coil packs and an ignition module that go bad so maybe one of those is bad. Check into that stuff and let me know what you find out.

In Reply to gmsteve455:
The motor is a 3.4L 24 valve V6. We initially pumped alot of water out of the tank via the valve on the top of the motor. But after I drove it home and it wouldn't start again, I put another 5 gal of gas in it and tried pumping it out again and nothing came out.
And No, My engine light never came on. But my gas gauge still reads 1/2 full.
Still wont start.

first thing you need to do is drop the tank and get rid of every drop of liquid in the tank. Then you need to flush the fuel lines. Install a new filter and refill the tank with fresh fuel. While you have the tank down, move the fuel level float by hand while someone watches the guage. If it still doesn't move (continues to read 1/2 tank) you need a new fuel sender, and while you're in it that far, you might as well replace the fuel pump and strainer.

Can you or anyone tell me how to "Flush the Fuel Lines"?
I don't mean to sound like a girl...... But "HA", I am.
Getting ready to drop the tank today, Yee Haw!
Wish me luck!

Thanks again for helping me!