ox66 VST pressure issues

[90MAKO230]

So i've been in the process of trouble shooting some issues with my 98 ox66225. recently i hooked up a fuel pressure gauge to the vst and when i turned the key the gauge only went up to 20psi and then started to drop off. i could turn the key again and the pressure would go up above 20 psi but then drop off again. Is this a sign of a bad HP fuel pump? or some internal leakage? i just recently pulled the injector and cleaned those. could one be leaking and not allowing it to maintain the 35psi?

[99yam40]

how do you know the gauge is reading pressure properly.
I would check the gauge to make sure.

no the pump will not keep running if the motor is not running