My 91 Wrangler gets gas to the rail but wont run. No pressure when I press valve. Replaced regulator. Starts and runs a little when I put some gas in throttle body. Any help?

More likely the pump is not putting gas up to the engine's fuel rail.
With key on, not start, the pump should turn on for 2 seconds to put pressure in the line and fuel rail. Do you hear the buzz or hum from the tank with key on?
Did you put a fuel pressure gauge on the fuel rail's test port (shraeder valve), and find no pressure with key on? If so, you will need to check into the pump operation (assuming the fuel filter is not clogged). A quick test is to pull off the gas tank electrical connector, find the fuel pump wire in the connector, and use a test light grounded to a metal frame or a voltmeter. Check for power on the fuel pump wire, while the engine is being cranked over. If power then, your new pump is not working. It could be the ground for the pump, so you need to check that. If no power to pump, engine cranking, then you will have to find the fuel pump relay under the hood, and check the wiring to it. There is also a fuel pump fuse-it may be under hood or in the instrument fuse panel-need to find and check it.
If the pump is working and the fuel filter is clean, you should have gas in the fuel rail (which supplies the injectors with fuel under pressure). I have not heard of a pressure regulator problem that could cause no pressure, but then...
Post back what you find, or with comments. Hope this has helped a little.

What is the fuel pressure when the engine is running ?
Has the filter been replaced ?

replace the fuel pump,the check valve that holds pressure on the fuel is in the fuel pump.The fuel in the lines is draining back into the tank

Fuel Pressure Regulator is located on the fuel rail.

1. Disconnect the negative battery cable.

2. Properly relieve the fuel system pressure.

3. Remove the air cleaner outlet tube(s).

4. Remove any necessary components to access the pressure regulator.

5. Disconnect the vacuum hose from the pressure regulator.

6. Remove the pressure regulator attaching screws.

7. Remove the pressure regulator from the fuel rail.

To Install

8. Discard the O-rings on the pressure regulator and replace them with new ones.

9. Lubricate the O-rings with clean engine oil.

10. Install the regulator into the fuel rail and tighten the retaining screws.

11. Connect the vacuum hose to the regulator.

12. Install any components removed to access the regulator.

13. Install the air cleaner outlet tube(s).

14. Connect the negative battery cable.

a oil gauge reading maybe delayed until car starts and builds good oil press.Did you check for spark
was car running good before this happened? Do you have a rpm reading when cranking car?

I take it you mean it WILL crank(turnover) but wont start. Anyway, Your problem may be a lack of fuel pressure. Could be the filter is now clogged. Trapped air in fuel lines, and fuel rails. Most GM vehicles have a schrader valve on one of the fuel rails. It looks similar to a tire valve stem. You could turn the key to on, make sure you hear the pump in the tank running. It will run a few seconds to pressurize the fuel system, and run continuously after the engine starts. Using a fuel pressure gage to check pressure and depress the valve carefully to visually see if fuel or air is present. Dont position yourself to be sprayed with gas.

Most late model vehicles wont arm the ignition(spark) systems unless there is correct fuel pressure, among other things. Something you may not know is that most all fuel tanks have a reserve of 1 to 3 gallons of fuel in the tank that wont register on the gage. Putting in 1 or 2 gallons most likely is not enough to prime the system. Hope this helps.

Hello, first of all,which motor do you have , and just because you had 60psi at that given moment doesn't mean that your pressure is going to be the same every time, the problem is that if the fuel pressure regulator valve goes bad and makes the engine start hard and then other times starts real easy and I put the fuel pressure gauge on the manifold and it said good pressure but when I took the vacuum hose off of the fuel press reg valve it was full of gas and that means that the gas is going by the diaphragm in the valve and letting gas right into your vacuum port, now if you have a 5.3 it's an easy fix , it is a little round valve about the size of a 50cent piece with a vacuum hose going to it and it is on the driver side on the fuel rail about in the middle , now if you have the 5.7 then it is little more complicated, you have to take the intake manifold of and the fuel press reg valve is underneath,. You might also want to check the ground strap going from the engine block to the body of the car. good luck.


Thanks

Dear Smoker.......Sounds to a trained ear that this little guy is gonna need a fuel pressure regulator. It is basically dumping an excessive amount of fuel with the black smoke and all and once it gets warmed up it runs a little better cause it's out of the closed loop cycle. Check the fuel pressure regulator...pull the vacuum line off of it and if you can smell gas or see gas drippin out....that regulator is junk!!! The pressure regulator is on the fuel rail on top of the motor by the way...this should cure your woes.....if not..please get back to me... I HOPE I COULD HELP!!!

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.

Sounds to me like the fuel pump is worn out. They DO wear out. And even though they seem to be working, the brushes in the electric fuel pump may not be contacting all the commutator, thus making the pump weak. It may start the motor but can't maintain normal running pressure (27-35psi). Have you run the car out of gas shortly before this problem surfaced? If you have then it's your fuel pump. It was damaged when the tank ran dry. Even though the pump may seem to be working, it's still badly damaged and needs to be replaced.
Just as Matmenzies has stated, get a fuel pressure gauge and test the pressure. I'd start with a complete check of all your vacuum lines. Check for cracks on the vacuum hose that connects to fuel pressure regulator on the fuel rail. Also, if you can, get a hand operated vacuum pump to check the regulator. If you can place a vacuum on the regulator and it holds, I'd say move on the fuel pump and check it.
BTW, if the fuel filter has been changed, you may want to check to see if it was installed backwards! Some fuel filters are valved and will cause symptoms like this. However, this is an immediately noticeable mistake and you haven't provided enough info for me to say more. I'd pull it and check that it has any flow at all. You could have sucked in a big dirt ball and blown it right into the new filter, effectively stopping fuel flow. Then I'd blow out the fuel lines, just to be sure.
Start with these 2 things and post what you find. We'll go from there.