1977 Chevy Nova Won't start or when started won't stay on

The fuel fitlter is located between the fuel ine and carburetor, I'm assuming you have rochester quadrajet as a carburetor. Remove the fuel filter and replace, If the does not work then your carb may need adjusting or rebuilt. I suggest try adjusting using the fuel mixture screws located on the carb. You also have a bad fuel pump. All which are relatively inexpensive to repair except for a new carburetor. A good way to test is to use starter fluid in the CArb. Get it started and the slightly press the accelarator to kep them rpm up while in park and hold for about 15 seconds if the car dies then the most likely problem is the fuel pump.