My blazer is having some kind of fuel issue. I will describe every detail so far. I purchased the blazer in feb 08 and in march replaced the cat converter followed by a fuel pump and filter a week later. In April It was the O2 sensor followed by another after another O2 sensor not the same one according to the shop at wich point I got my scan tool. I then parked the truck and haven't driven far since due to worn bushings. I replaced all front bushings and plug, cap, rotor, oil, filter, and cleaned the k&n filter last month and went for a drive to see how it went, fine at first then it started to smell rich again and burn black smoke so I figured possibly the injectors due to it being the only fuel system part untouched. I pulled the injectors and had them rebuilt and a new pressure regulator, as I installed I ran a blast of compressed air down return line per shops request to insure no clog. now running smoother but stiil smell fuel and burning black smoke.

 

How do the rest of the sensors check out? Any exhaust leaks ahead of the upstream O2 sensors?

 

All sensor check O.K. I just threw some codes wich were multiple engine missfires, engine rpm too high, catalyst too low, and engine rpm too high yet apears to runs fine other than the smell and smoke.I drove for about 10 miles with the check engine light on and no hesitation, stalling or uneven idle non at all runs smooth as new. So I then reset the light.
No exahst leaks in system

 

After I reset the check engine light I filled up the gas tank and drove the Blazer untill the light came back on, I drove 133 miles before the light reappeared. This time it was throwing P0131 O2 sensor low volts sensor 1 sensor 1 bank 1, P1133 Heated Oxygen Sensor (HO2S) Insufficient Switching Bank 1 Sensor 1, and a pending P 0131. I made note reset the light and drove home and the light came on this time after about 5 miles. After I got home I rechecked the the codes and this time it was P 0131 and a pending P0131. I have the O2 sensors to replace and I am waiting on a cat converter now. Any other suggestions

 

Have you done a compression leak down test on each cylinder? Black smoke out the tail pipe is also a sign you've got blow by on the piston rings.

 

I've had a compresion test and leak down performed already. all cylinders checked out fine. And correct me if I am wrong but isn't Black smoke excessive fuel while blue smoke is oil and white is coolant or water? Just replaced O2 sensor bank 1 sensor 1 and reset engine light. so far so good.

 

After the new sensor went in I drove for 10 miles when the check engine light. I checked it P0131 O2 sensor bank 1 sensor 1. I reset the light and continued my errands. After about 5 miles the light came back on throwing code P0171 bank 1 too lean so I reset the light and drove home to change vehicles. by the time I got home the light was on again, this time it was P0131 and P0171. could this be a faulty sensor??? And the black smoke is so bad that I can often times loose sight of the vehicle behind me. Not too mention the extremely rich fuel smell