Not necessarily, that screw just adjusts the tension of the spring that pushes on the diaphragm. Changing the diaphragm doesnt mean you have to adjust it for pressure. Now if you had to change the spring and that little metal bowl thing, then I would imagine it would need to be adjusted properly. No problem. Hopefully all your problems will be solved. If you do the fuel pressure gauge, let me know what all you cobbled together for it as I'd like to have it when diagnosing issues.