Pump runs for about 1/2 hour stops starts in a few minutes and stops again and again

have your alternator checked,it may not be working and is not charging your battery,thats why it dies so fast and won't start again.

Vent valve has failed closed or cannister is clogged up. Have the evap system checked from the tank to the charcoal canister. If you need to drive to a mechanic, try driving with the gas cap loose.

The pump is defective and will need to be repalced.

sounds like your motor is overheating or going bad. sometimes lint built up around the motor can cause it to overheat. or the motor is dying.

Sounds like your motor is overheating, This is a sign of windings going bad and sorry to say you will probally have to replace the motor.

Sounds like dirty gas and the fuel filter is clogged...try changing the fuel filter...some are under the car, but most are mounted against the firewall in the engine compartment.

Some GM products also incorporate the oil sender switch into that circuit for fuel pump, so that in case of an accident, engine shuts off, oil pressure drops, in turn, shuts off power to fuel pump. May be worth a look at what your getting for oil pressure, as well as checking switch/sender.

check motor with hand after it stops for excessive heat. Thermo coupler shuts motor off if overheating, to protect windings. Bad motor bearing can cause overheating, if so should hear bearing noise when running.
Also check start capacitor, by removing and checking with ohm meter, or plug in oposite terminals of capacitor to charge. Place rubber glove on hand, and contact two oposite terminals with screwdriver should produce a small spark.

Your fuel pump is sticking and not pumping, this is common if you run the fuel down to less than 1/4 full, the fuel pump needs the gas to cool itself, below a 1/4 tank the pump is not getting cooled and after repeatably running low on fuel it overheats and fails. Running the car near 1/2 tank extends the pump life to many years more than running tank below a 1/4 full..