NEED EXPERT HELP 1995 chevy blazer 4.3 will not start

My 1995 chevy Blazer 4.3 will not start. I have Narrowed it down to fuel. spark is there and air is there. it will start with starter fluid, but it wont keep running. changed fuel pump it did need changed. Changed fuel filter and fuel is coming through the lines past the fuel filter. but No fuel to the injectors. is there another place it could be getting stopped.
Please offer suggestions. Thanks

If yours is a VORTEC... read on! It may be the
Fuel pressure Regulator. more specifically, the CPI unit, which contains the FPR. First, let me start with a brief description. The CPI unit is sometimes referred to as a "pod" or "spider." This unit consists of a main body that houses a fuel injector and a fuel pressure regulator, and six small tubes that deliver fuel to each cylinder. http://www.asashop.org/autoinc/feb2000/img/tt1.jpg
At the end of each tube is a poppet nozzle that contains a check valve and spring to regulate fuel flow. Fuel will flow from these nozzles when pressure exceeds 37 to 43 psi. The fuel injector has six small holes in the bottom that supplies fuel to all cylinders at the same time. This system is not sequential. If there is a problem with either the injector or the fuel pressure regulator, the entire unit must be replaced. These components cannot be replaced individually.
Standing pressure on these units should be around 59 PSI.
There are several places these units can leak fuel. Watch for leaks around the injector electrical connector. The lines coming in to the vortec unit are plastic like the tubes and are also known for cracking and leaking. Also, look closely at the fuel pressure regulator. Even if your system holds pressure, it may still be a good idea to take a closer look at the regulator.
These units cost around $320, but are a worthy investment.

A really quick way to check if it is your fuel pressure regulator is to look inside the intake manifold. Pull off your manifold tuning valve and shine a flashlight in there. If your manifold is black and crusty then your spider is ok. If it looks clean inside there (goldish) then something in there is leaking fuel.

If your passenger side is clean then it is likely your fuel pressure regulator is leaking. If the driver's side is clean then the inlet/return lines may be leaking.

If you replace the fuel pressure regulator or even the whole spider make sure to replace the inlet/return lines (also known as the nut kit). They're cheap. It's worth your while.

make sure you chech to see if you have fuel pressure. don't know if its been said that it was done.

thanks will try.