I have a 94es300 i crank it it starts up runs 5 mins shuts off like not getting enough gas changed fuel pump, fuel filter , fuel pressure regulator and ignitor still same whats up with this car

Several GM cars of mine had check valve in fuel filter. I stopped the delay in cranking by changing the fuel filter. I think Nissan fuel pressure regulator act as a check valve. The issue of it taking a while to crank sounds like the gas may be running back to the tank and you have to pump the air out of the line before it cranks. Just a thought to look at, fuel pressure regulator.

Could be a fuel pressure regulator not working. Thus ecu complaining about fuel Pressure. probably not enough because the regulator is worn and leaking down so will not maintain the proper pressure. You will need to google the make model and fuel pressure regulator to find it's location or library and repair manual. Otherwise, you need to measure the pressure and find the spec for the required fuel pressure. Probably somewhere around 120PSI

Did you change the fuel filter when you changed the fuel pump? If there was any water in the gas, it can cause the filter media to swell and effectively plug an otherwise clean filter.

It sounds like your car isn't getting the proper amount of gas. You say your mechanic changed the fuel pump and the regulator. Id have him run a diagnostic tool on it to see if it throws any other codes. Its getting fire. Try changing the FUEL FILTER. it maybe clogged. maybe the pressure regulator is not giving it enough pressure to push the gas into the engine or maybe the fuel pump is only working at times. Does it run good and then start to spit and spudder then die? if so its not getting gas some how. Idk if you can adjust the pressure regulator or not. i mostly work on old school cars.

check your fuel pressure and volume for the pump. Fuel pump may not be supplying enough pressure and volume to keep engine running. also on your fuel rail,on the engine, where the fuel line attaches, should be a fuel pressure regulator. where the fuel line attaches on the regulator should be a screen, see if dirty and clean.if pressure over 32lbs chances are regulator is inop ,or fuel return to tank blocked.

Ever check fuel pressure at the motor

The fuel pump could be as old as the truck
& worn out

Has the filter ever been changed?

Ever look at any data on a road test with a
professional scan tool

Do a fuel pressure test. If you have compression, and good spark, this is where you should start.

sounds like you are running lean , i would start by changing the fuel filter and check for fuel pressure using a fuel pressure guage at the shrader vavle on your fuel rail, if your fuel pressure is not above 35psi when you cycle your key on and you have changed the fuel filter i would recommend changing the fuel pump,

Measure fuel pressure on injector rail - should be 38 to 40 psi. If low or fluctuating, then replace regulator. Another possibility is the in-tank filter being clogged - rare I know, but trash in the gas tank and it's clogged.

this year model is notorious for fuel related probs...check the remainder of the fuel system, injectors, and the fuel pressure regulator also verify that the fuel pump is actually running and getting the correct amount of power to the pump itself..... it may not be bad just not getting enough power