A weak fuel pump can cause lack of fuel on high end.
A fuel pump putting out too much fuel can over fuel the carburetor causing it to flood.
Pressure Test
Use a suitable fuel pump tester. The tester should be able to test at low pressure such as 4 lbs. Injected car fuel pumps are tested at much higher rates.
Remove the coil wire so the car does not start.
Crank the engine for 5 seconds or so. Pressure should be close to 4.5 lbs.
Capacity Test.
Be sure the fuel filter is clean and there are no kinks in the fuel line. Perform this test only when the pressure test is within specifications. Open the petcock, and expel the fuel into a suitable container. Operate the engine at 500 rpm and observe the time required to expel on pint. It should be 20 seconds or less.
