I have a 2001 Blazer 4.3L VIN 1GND13W01K194010 that started running sluggish recently. Starts fine idles fine runs rough or will not accelerate when I hit the gas a moderate amount. I recently replaced the following parts: cap (duralast), rotor (duralast), spark plugs(delco rapidfire), wires (autoliote pro), fuel filter(mfg ??), air filter (fram).

I cleaned the MAF with MAF cleaner. I checked the fuel pressure at pressure port with key on which is 59-60 psi. When shut off it holds this pressure for 10 + minutes. When I bleed down to ~10-12 psi it also holds for 10+ minutes. While running the gauge fluctuates between 52-54 psi. (thanks to swartlkk 96+ fuel system diagnosis post).

I added 2 bottle of dry gas to the last fillup to be sure it was not water in the fuel. I can not find any vacuum leaks in any lines. I removed, clean and reattached all emmission components I could ID (throttle position sensor, MAP, intake air temp).

I have read many threads on this forum and have tried most tests I could. Please help. Driving me crazy and keeping me up nights.

 

maybe it just needs a cleaning...my 1st gen before i sold it..i took it to sears for a fuel system cleaning..it took off like a jet so much afterwards i actually reconsidered selling it...and its 90$s..but well worth it IMHO........we can't remember the name of it..but i just put a bottle of some kinda fuel system cleaner in my 2nd gen and it fly's now..from moms house to mine it used to take almost an hour and a half and about 3/8 of a tank...this last trip i didn't realize i was doing 75 the whole way..(which isn't usual for me) it ran alot smoother and quieter..and used 1/4 of a tank i actually didn't want to come home i was so happy with how it was running..but at advanced auto its in a red bottle with a black sticker in a long narrow tall bottle..neither of us remember what its called though...but i plan on sticking with using it i' so happy with it..

maybe you just have built up engine goo?...

 

thanks mudbunny84 for the reply. what was actually done for the fuel system cleaning you had done at Sears??? Also does Chevron Techron or Redline ring a bell for the cleaner you used?

 

does anyone know if the pressure reading I am getting on the fuel rail seem okay? 59-60 psi at key on, 52-55 and fluctuating while running. I am wondering if the pressures are too low and may be a problem for good injection? I have 145k on the truck and it all of a sudden started acting up.

 

SOLUTION: After replacing all of the above usual components (plugs, wires, cap, rotor, coolant temp sensor, fuel filter and fuel pressure regulator (including new gasket set for plenum) I checked the EGR valve and cleaned it, checked my O2 sensors for bad connections or no codes from OBD2 I still had a lean code and no vacuum leaks (I built a smoker to smoke the manifold) after replacing a PCV valve and PCV vlave elbow. The pressure seemed to drop off on my gas gauge from 59 psi at key on to <40 psi in 10 minutes which was worse than before when I tested it. I changed the fuel pump with an AC Delco MU1733 I think it was and my lean codes and trouble are gone. Granted, from neglet much of my parts I did replace were in need of it anyways, but the fuel pump seems to have done the trick. If have not yet retested the fuel pressure to see what it is now, its too hot and I am too tired right now.