Need wiring harness for fuel pump. Does anyone know where one can be obtained or a part number?

Here's a wiring guide for the fuel pump on a 2000 Cadillac Deville: 1. Remove the fuel tank and access the fuel pump module. 2. Disconnect the electrical connector from the top of the fuel pump module. 3. Locate the wiring harness that runs from the fuel pump module to the car's electrical system. 4. Cut the wires on the old fuel pump module connector, leaving enough wire to splice the new connector onto. 5. Connect the black wire from the new fuel pump module connector to the black wire in the car's wiring harness. 6. Connect the purple wire from the new fuel pump module connector to the purple wire in the car's wiring harness. 7. Connect the gray wire from the new fuel pump module connector to the gray wire in the car's wiring harness. 8. Connect the black/white wire from the new fuel pump module connector to the black/white wire in the car's wiring harness. 9. Connect the new fuel pump module electrical connector to the car's wiring harness connector. 10. Reinstall the fuel tank. Note that it is important to follow the wiring guide carefully to ensure proper installation and avoid damaging the fuel pump or electrical system. If you are unsure about any step of the process, it is recommended to seek assistance from a professional mechanic or refer to the vehicle's service manual.

The fuel line my have someing in them or the fuel futer my be bad

BYM, Back Yard Mechanic...You will need a Mechanics Manual...Chilton's, Haines, or OEM...Look thru the wiring diagrams, BEFORE you start dicing, and splicing...as far as your real problem...did you replace the Ignition Control Module, that is inside the Distributor cap??? It's Black, and has several wires that attach to it...those are the 1st thing you want to look at, before you start messing with the fuel delivery system, Buy A New ICM, or 2, and replace it, it's good to keep a spare around (in your vehicle). You will need a 7 mm socket, w/extension, and obviously, a driver of some sort, ratchet, or nut driver type. Good Luck.

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

Gray is the B+ power for fuel pump , black is ground for the fuel pump ! The other two wires are for the fuel level sending unit .( gas gauge )

here is the part number for the fuel pump kit from Carter, everyone carries Carter.
CARTER Part # P74000 {In Tank Fuel Pump}Includes Wiring Harness $38.79

It's common for the wire harness from the pump to the frame to go bad when the fuel pump is replaced. The harness is around $15.00 and should be replaced the same time the fuel pump is replaced. If you can get to the wire harness to move it around and see if the fuel pump would start to work, then you know it's the wire harness and you can also disconnect the wire harness at the frame to check for 12v. Food for thought also, was the fuel filter replaced shortly after the fuel pump??? It may have picked up dirt that got in the gas tank and is not to dirty to let fuel flow through. Good luck and keep me posted.

Use lots of wd40 on tank strap bolts. If they bigin to bind tighten them up and losen again to get rust out of threads. If you remove the straps, why not remove the fill neck and lower tank? Much easier to work that way!!!

The sending unit sends a signal to the engine control module. The engine control module sends a serial message to the fuel gauge.
Check the connection at the fuel tank. If you have a digital multi-meter, check the resistance on the "purple" wire at the fuel tank connector, fuel tank side. The amount of resistance will be determined by the amount of fuel in the fuel tank. Generally it should be between 10 and 255 ohms.
Below is the wiring diagram for your car. Hope it helps, let me know.
Regards.

well does your fuel pump kick on when you turn the key if so check the spark plugs and wires if not check the relay to your pump or check the fuze and see if it is blown or getting any power to it