02 R50 Pathfinder wont start

[Nolimitbt]

I have a 2002 Pathfinder with a 3.5L R50 motor that most of the time will not start again after the 1st start. It always starts right up very easily on the first start. It makes no difference if engine is warmed up or cold. The engine turns over and sounds normal but won’t start. I can smell a little gas when engine turns over and doesn’t start. Checked for spark and we are getting spark. Have to let the car sit overnight 6-8 hours, and then it starts right up again.
I hooked up a fuel pressure gauge to an adapter with a Schrader valve that fits under the fuel damper made for Pathfinders. The results are:
Just turn key on prior to starting and the fuel pressure is 40 lbs,
When the Pathfinder starts while idling: with vacuum hose connected to fuel damper the pressure is 34 lbs. Which is within specs.
With vacuum hose disconnected from fuel damper, pressure Approximately 41 lbs. again within specs.
When the motor won’t start and it’s just turning over the fuel pressure is 40lbs
I removed the vacuum hose from fuel regulator and plugged the vacuum hose, then connected a vacuum pump directly to fuel regulator and applied vacuum and the fuel pressure decreased like it supposed to. (Within specs)

I also connected a vacuum gauge to the vacuum hoses that go to the fuel regulator and the fuel damper and had good vacuum at 20psi.
During the Fuel pressure test I discovered by holding the button on the fuel pressure gauge that releases pressure and bleeding the fuel system I can get the motor to start every time. After engine starts I let go of the release button and engine runs good like normal, turn off the motor and try to restart it and it won’t start unless I hold the pressure release button and bleed the fuel system and then it starts.
I replaced fuel pressure regulator because I thought the regulator wasn’t releasing the gas back to the gas tank and building up too much pressure. It didn’t solve the problem or change anything…. I need help, can’t figure it out.
All injectors are new, not the cheap Chinese ones and pulled the fuel rail with injectors connected to make sure no injectors were not leaking.
No OBD2 codes, Please help.

[mdmellott]

Fuel delivery sounds right from what you described. I would first suspect metered air flow issues, as in a faulty or dirty MAF sensor, cold air intake leak, or a vacuum leak somewhere may be the culprit.

[Nolimitbt]

I Have cleaned very well the entire throttle body including the MAF sensor, and replaced the Idle air control valve. It did not make any difference. I checked the vacuum right at the intake manifold and it's a sold 20psi. I have checked and replaced all of the vacuum lines. What I don't understand is why I can get it to start only if I bleed the fuel lines then it will fire right up. I also have a high Idle around 1150rpm even after engine is warmed up and driven.

[VStar650CL]

Have you checked for wet plugs when it no-starts? Nothing Nissan will start up flooded, so one or two leaky injectors can easily cause a balky-start or no-start. That would make sense with reducing the fuel pressure, it may be letting the cylinders clear themselves out. An over-indicating MAF can also cause a flood, because the ECM adds too much fuel thinking more air is arriving than what's actually there.