Fuel rail pressure should be 40psi. Measure after fuel filter with an inline gauge. When the key is switched to ignition the fuel pump will run for about 5 seconds then switch off. The fuel pressure should rise to 40psi rapidly not slowly. The fuel pump will turn back on once it receives an ignition signal(engine started).
If the gauge rises slowly or doesn't reach 40 psi, chances are the pump is on its way out and will need replacing. Hard starting and bad performance can result from low fuel pressure.
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