How to test fuel pump

Bleed the fuel system after checking the pump.

Fuel pump electrical circuit diagnosis no fuel pressure testing GM
GM Fuel Pump Relay Testing

Disconnect the wire connection to the fuel pump, turn it on and test for 12V (or whatever your car battery voltage is) at the leads coming from the battery. If 12V is present the problem is the fuel pump. Test the continuity of the pump circuit at the same time (no power on for this test). set VOM to resistance attach to both leads going to pump. If reads 0.00 continuity is OK. If no reading pump circuit is open, pump motor is bad. I have had them bad right out of the box. Good lesson to learn whenever possible, ALWAYS bench test new parts before installing.

Do you have a test light? If not, go buy a cheap $5 test light-one with a lead to clip to a ground, and with a needle type probe.
Pull the fuel pump relay out of the terminals it is plugged into-you need to check if the power feed for the pump is still available at the relay. Clip the test light lead to a ground and touch the test probe to the positive battery post-to check that your ground is good- tester should light up. Now touch the probe to all of the terminals that the relay plugs into. One terminal should have power with key off. If no terminals have power, you have lost the power feed for the pump. Double check all your maxi fuses in the power distribution box. Either a maxi fuse or a fusible link will be the power feed for the fuel pump relay.
If the power feed is there at the relay, try a new relay. If still no pump, a shop will probably have to check your fuel pump circuit.
Did you check for power at the fuel tank while the key was held in crank? When the engine is cranking, the fuel pump wire should have power. When the key is turned to on, the fuel pump should have power for about 2 seconds, to pressurize the fuel system. Then when key is turned to crank or start, the fuel pump should stay on.

No one can diagnose any vehicle problems without the patient

You need wiring diagrams & a volt meter, to test the fuel pump
circuits you suspect being an issue

Was the old pump bad or never tested either?

Get a test light and test the wires going to it ground one end and see if you have power at the pump. If not do the same at the fuses so where you are not geting the power.

Yes , Do you know what scan data is ? Sensor data ? What a scan tool is , not a code reader .
002 Fuel System Tests Start Here
003 Fuel System Tests Scan Data Tests

WHAT KIND OF FUEL PUMP DID YOU BUY GM OR AFTERMARKET,ALOT OF THE AFTERMARKET ONES YOU HAVE TO CUT THE ENDS OFF OF THE PLUG AND CRIMP THEIR NEW ONE ON.I GUESS THEY HAD PROBLEMS WITH THE PLUG GOING TO THE FUEL PUMP GOING BAD.OR YOU COULD HAVE A GROUND WIRE THAT CAME UNDONE.THEIR IS ONE THAT BOLTS TO THE FRAME NEAR THE FILLER NECK AREA.LOOKS LIKE A GROUND STRAP,CHECK TO MAKE SURE THAT IT IS STILL ON.GET A TEST LIGHT JUST TO MAKE SURE THAT YOU DIDNT GET A FAULTY NEW PUMP.TEST THE PLUG GOING TO THE FUEL PUMP SHOULD BE HOT WHEN YOU TURN THE KEY ON ...MAY NEED 2 PEOPLE.ALSO CHECK TO SEE IF YOU ARE HOT UNDER THE RELAY WITH YOUR TEST LIGHT.RELAY SHOULD CLICK.ALSO MAKE SURE YOU HAVE NO SECURITY ISSUES,WITH KEY OR ALARM KILLING POWER TO PUMP.GOOD LUCK

you can't increase voltage , sounds like bad pump or bad ground

buy a cheap test light/probe and use that at the fuel pump plug to check for power in that circuit.It could also be a relay thats at fault so check that for power in and power out,same test tool.There are not many wires at the pump plug but as long as only one has 12v its not a power supply problem.Does the car run at all?