Pulled off fuel line to the injector rail and it started till it ran out of gas.changed fuel pump,regulator and injectors,good spark to plug,but if I pull off line again it will run help please

Hello. It seems your Nissan is 'flooding' with gas; the fuel pressure regulator is NOT sending gas back to the tank. It's also possible the vacuum hose going to the fuel pressure regulator is faulty/defective. Good luck and keep me informed; if you want to.

Usually if cranks good but won't start, you have a helper crank it while you visually check for spark at the spark plugs. If spark everywhere, use a gage and check proper fuel pressure and check fuel injector pulse. I don't know what testing you have done?
As far as the fuel regulator, it depends? If there is a return line, the pressure regulator should be on the fuel rail. If no return line, with mechanical returnless, the regulator may be in a loop close to gas tank. With electronic returnless, everything is in the gas tank. Sorry, I haven't found any pictures?

Fuel pump dead or dying. Injection systems need 110 psi, and a pump only doing 30psi will still not run .

The crank position sensor could be bad.Check the injectors & fuel pressure regulator with this test.Hold the gas pedal to the floor while you crank the engine.Does it start??If yes,the fuel pressure regulator is bad or you've got a internally leaking fuel injector.Let the engine idle,pull the vacuum hose off the regulator and see if gas is inside the hose or gas is seeping from the regulator vacuum port.If yes,the regulator is bad.You can shut the engine off,wait 5 minutes then pull all of the spark plugs.If a plug is wet with fuel,that cylinders injector is leaking.A bad ignition module or ect sensor can also cause a no start.You can do the following test when the problem is occurring.Remove the air intake hose from the throttle body,spray carb cleaner or starting fluid into the TB opening, reinstall the hose,try starting the engine. If it starts and runs for a few seconds then dies,you've got a no fuel problem. If it doesn't start at all,you've got a no spark problem.

Here are your possible problems. 1)Leaking injectors(Rare), Leaking Fuel Pressure Regulator(Common) Bad Engine Temp Sensor. (Common), Here is what i would check. Find the Regulator and pull off vacuum line, (located on fuel rail near injectors) check if there is fuel present in line. If yes replace regulator. Check temp sender with a scanner your looking for a reading in the (-) or below 140deg F, when car is first started and smoke present if yes replace engine temp sender for computer(not sender for guage!) IF both those pass inspection replace injectors(Not common problem)

You said, 'fuel injectors are not injecting fuel into fuel rail' but it's my understanding that the fuel rail gasoline is supplied by the pump, and the fuel injectors just pulse to allow fuel to get to the cylinders. I would check out the fuel delivery problem further. Check for pressure in the fuel rail that is within specs.

If not, then the pump or fuel pressure regulator may be the problem. Check the fuse for the fuel pump. If good, then the pump may be bad in the tank.

Good luck on this.

I think it's possible that the fuel regulator is stuck open and allowing the fuel to return to the gas tank. If your car is like mine (1991 Acura 1.8 engine), you can try this experiment: Pull the vacuum line off the fuel regulator (it's on the end of the fuel injector manifold and a hose connects to it to return gas back to the gas tank) and temporary plug the hose with a small bolt or golf tee. If the regulator is not stuck open it will make the fuel injector manifold at the highest pressure. Start the car and see if it dies or keeps running ok. If it runs ok then the vacuum control is not working right. If this doesn't help, try changing the fuel regulator valve or pull it out and test it with a vacuum off and on. When the vacuum pressure is present to the valve the valve is suppose to open slightly, this allows fuel to bypass the fuel rail and return to the tank.

I had exactly the same problem when I bought a ford pu last year for resale. 4 injector wiring lines were chewed through. I tried starting it before I fixed them, and it ran on the other 4... but it did foul the plugs that had chewed lines, so I changed them & that solved the problem. So if you have the right fuel pressure at the fuel rail, and your injector wiring has been done correctly, i would not buy new injectors until i put new plugs in those cylinders.

is there air in the fuel rail? bleed air bubble out

This injector set-up needs a specific fuel pressure supplied to the fuel rail to even start, much less run properly. The fuel pump is immersed in fuel inside the gas tank to keep it cool and not burn up. Running the fuel level low causes more heat in the pump and interuptions in proper fuel pressure. AC/Delco pumps have proven to be a reliable fix, the aftermarket pumps only last for a month or two sometimes. Check fuel pressure under the hood and power and ground to fuel pump at electrical harness at top of gas tank. This truck needs a fuel pump.