1996 Blazer fuel pressure test
I have a 1996 Blazer with the 4.3 engine. Lately I've been having problems starting it, had to turn the ignition on and off a few times to get it to start. Last week it started loosing power and bogs down if you don't feather the throttle just right. I did the fuel system diagnostic and it has 60 psi at first and it drops to 56psi after ten min. with the ignition off. The fuel pressure is 60 psi with the engine running, but the guage fluctuates very quickly between 50-60 psi. When I throttle it it fluctuates between 45-60 psi and bogs down in park.
I replaced the fuel filter and the center part of the old filter had broken loose, so it wasn't doing a thing. I started thinking the spider assy was plugged because of the fuel filter so I replaced it with another spider assy from another blazer I have. When I took the plastic cover off of the intake I noticed that the intake runners at he rear were shiney clean and the rest were black and dirty so I guessed the pressure regulator was leaking. I put the other spider assy in and hooked the fuel lines up and jupered the injectors one at a time. They all sprayed well and nothing leaked so I put everything back together, but it still runs the same.
Its not throwing any codes right now but it did throw an O2 sensor low voltage a couple times while I was throttling it and it was running bad.I replaced the ignition module and coil from the other blazer as well. I guess I'm wondering why the needle on the fuel pressure guage is fluctuating soo much under load is this normal?