Hello I have a '97 blazer and here are my issues:
1) Fuel system is not up to par. The blazer has 4.3 Vortec w/ multiport fuel injection and I have to let the fuel pump run prior to attempting to start the truck.
-I have attempted to check fuel pressure:
w/ key on the pressure jumps up to 61 psi and immediately bleeds off to zero.
@ idle the fuel pressure is 57 psi and holding.

An ironic problem that I corrected yesterday was that when attempting to start the truck I would drain the battery so yesterday morning I pulled the battery from the Jeep ('76 CJ7) and put it in the blazer and the blazer fired right up. I took the battery to AutoZone and it tested as having a dead cell.

As I stated the blazer will start only after "priming" by letting the fuel pump run first before turning over the engine and then runs fine.

Let me know what you guys think - fuel pressure regulator?? or fuel pump??

I tend to believe the fuel pressure regulator, thanks.
jml

 

There is a small fuel line connector at the rear of the plenumn on the drivers side when you have the upper plenumn off it will be on the drivers side rear where the hard fuel lines come into the plenumn and attach to the flexable lines. These lines also come loose and leak at this connector also. You should be able to see a clean spot on the bottom of the plenumn valley where any fuel has been leaking. This part is about $50.00 compared to the price of a CPI unit.
Or the flexable lines on the CPI unit are leaking causing the fuel pressure not to hold. Pull your oil dipstick and see if the oil is real thin and smells like gas.