Trouble starting hard starting

I have a 1996 (LS) 4x4 mid-size blazer with the 4.3 vortec engine, 115,000 miles, automatic. Im having trouble starting, having to hold key for long period of time before it fires, acts like its not getting fuel, you can heaar the pump run foir a few seconds then the relay will click, I do this a few times to prime the system when I have trouble starting the engine. I have not done pressure check on pump yet, I do have spark, today is the last it ran, it no longer runs, it will crank but not fire, still can here pump and relay, I have been told it may be the pump, but could be some part on the fuel plenium thats not aloowing fuel to travel thru, I know a good bit about older stuff but not to much on all the new electrical parts, any idea what or where would be the best place to start is greatly appreciated.