came to the conclusion after testing the fuel pressure that its a pretty good chance its the fuel pressure regulator i looked thru my chilton and hanes books but i not certain where the fuel body meter is located and that is where its says its at on the truck its a 2001 4.3 liter blazer the books are kind of vague on the location. can someone shed some light on the location so i can change the fpr. thanks

 

The FPR (#14 in the first image below) is located on the back of the SCFI injection spider body (#1 in the first image below) under the upper intake plenum (3rd image shown), between the TB and the distributor. I can't remember what all required removing, but when I took my upper plenum apart, I removed the TB, fuel lines, and anything else that may have been in the way of the upper plenum.

What were your findings on the fuel pressure?

 

If you tested your fuel pressure from the relief valve behind the plenum and it was low, your problem is NOT the pressure regulator as it is beyond that point in the fuel system.

In my opinion, opening up your plenum is opening up a new can of worms for whatever you think your engine problem is. If you crack one of the FI lines (fragileplastic like hoses)inside the plenum, you are looking at $400+ for replacement parts alone. The fuel pressure regulator will generally last longer than your Blazer.

 

FPRs are a known weak point especially on the older CPI motors. Not so much on the newer SCFI motors, but it still can happen.

I would say that if the fuel pressure rises up to around 55-60psi, then once you turn the key off, it starts to drop, then you either have a faulty check valve in the pump (unlikely), a faulty fuel injector (would be able to tell from the plugs), or a faulty FPR.

And I have had my upper plenum off before for no other reason than to change the o-rings in the fuel injection spider. I would think nothing of pulling it again. In the older CPI systems, the nut kit is fairly fragile, however it is no $400 to replace. On the newer SCFI units, you'd be hard pressed to break one of the runners from the central injector pack to the poppet valves. I don't mean to drop the thing on the floor, but if you are careful with it, you shouldn't have any problems.

*EDIT* - If you do end up finding that it is something in the injection spider, a new MPI spider can be purchased that replaces the SCFI unit with 6 injectors located out at the location of the poppet valves on the SCFI unit, completely removing the problematic poppet valves from the system. It is a direct replacement. I posted a PN awhile back and it was basically cheaper than replacing more than 1 injector/poppet combination.

 

well the problem that mine is having is hard starting. you'll have to crank it for several seconds to finally get it going. once it starts it runs like a champ with no hesitation when you step on it. so I put a pressure guage on it and its slowly drops after turning the engine off. what its acutally doing is its flooding. I took the air intake off after its been sitting awhile and I smell raw gas. but run it for a few and take it off and theres no smell of gas. also when i'm cranking it if i lightly put my foot on the gas when I first try starting it it'll start up pretty quick verses not putting my foot on the gas so it seems like its clearing the flood. so that why I was leaning towards the fuel pressure regulator or something else in the fuel meter body. I haven't changed it yet but will be doing so soon.

 

Try waiting 1/2 to 1 second after turning the key to 'on' before starting, let the fuel pump cycle and pressurize, if it can... It won't fix anything, but it might help make starting a little easier... Assuming it doesn't just fill up your cylinder...

 

yeah i've tried letting the fuel pump cycle before starting it and i didn't help any it still did the exact same thing. thanks for the input though.