Fuel check 2001 4.3 2500 GMC van

My van will not start. I replaced the cap, rotor, and plugs. After further checking I am gearing toward a fuel problem. I replaced the fuel filter and checked fuel pressure to be:
after guage (pressure released) is installed with no pressure 1st key on pressure to 10 psi, 2nd key on 20 psi, 3rd key on 45 psi, 4th key on 50 psi max. Then while cranking engine, engine does not start. After cycling the ignition switch several times turning the pump on, the engine does start sometimes. I drove it but lacks power. I am not able to buy a manuel as one is not available for this van yet. I looked at a 96' manuel, and pressure is said to be up near 60 psi. Would this difference in pressure cause a no start condition?
Mahalo in advance for any help. Dealer is not an option.

Pump needs to be replaced.

Hope this helps.

What leads you to the pump? Was it the scaling up in pressure with the on off ignition?
Mahalo

You are right. I did another check and found the static pressure to be 50ish, but flow is very little. Replaced the fuel pump @ $397.00. Van runs cherry.
Mahalo for your help.