99 4.3 w.160,000 miles. new fuel pump,filter,plugs,rotor, cap 6 months ago.did a fuel pressure test,turn key on 64 falls to 0 immediatly. at idle 54. is it fuel pressure regulator or?

Yip, could very well be.

That or the check valve in the sender is not staying closed.

I thanks for reply, any way of checking check valve in the sending unit.if it is check valve do i need to replace the whole fuel pump unit?

I thanks for reply, any way of checking check valve in the sending unit.if it is check valve do i need to replace the whole fuel pump unit?

If it was me, I would replace the pressure regulator before I started dropping the tank.

hi I replaced fuel pressure regulator and plenum gasket. It cured the problem,runs like a top.plenum gasket was bad so I realy don't know if regulator was bad or not.Took me 4 hours to do the job. I' ve never done it before. I learned a few tricks. thanks for your help. Mike

no problem.