Fuel pressure leak??
 

hey guys! I have a 94 xj with the 4.0. A little over a year ago I did the injector upgrade with Bosch 703s from eBay. When the jeep is running or has just been shut off I have plenty of pressure at the rail. I can press the schrader valve and fuel will shoot out. However, if I shut the jeep off after as little as 1.5 hours there is next to no pressure at the rail.

So, my question is one or more of my injectors bleeding off into the intake? Or is there some kinda of check valve at the fuel pump? How can I trouble shoot this to figure out what is going on? Thanks in advance!!! :)

It can be both

Does the oil has any fuel smell? if so, it could be a leaking injector.
If not, I will shoot for the fuel pump check valve.

No noticeable gas smell in the oil. There is however a strong gas smell I the intake of I take the air filter tube off and open the throttle body...

Can you see any puddle or gas if you open the throttle body and direct some light to the bottom (use a led light or something that does not emit any sort of spark), some gas smell is normal, but too much could be a fuel injector leaking.

Not sure how it goes on your location, but in my country I can get the injectors checked and cleaned for a total of 40 dollars, this will include the ultrasonic cleaning, flow check and leak check, I will do that before jumping to the fuel pump.

No puddles of gas, but it does look a tad moist in there...

Moist could be caused by oil blow by, or a bit of gas, not definitive answer on it, you can try to scratch a bit of that moist surface with a long screwdriver or something that reach the bottom of the intake, just to be able to pull out some of it and be able to touch it and even smell it.

I will have the fuel injectors checked first, before jumping to the fuel tank department that takes some more job to be done.