I've listed this once before. Installed a new fuel, verified that it was the correct pump for my 96 Tahoe. Had fuel pressure regulator checked and it's okay. Just got done changing out my front two O2 sensors. The Tahoe runs much better with the new sensors but the rich fuel error came back. What do I do now? Is it the Mass Air Flow Sensor? But wouldn't that cause lean full?

Do you top off the gas tank?If you do that,stop doing that.It will set off an oxygen sensor code off and over pressurizes the system.It happened to my grandma's 2000 Saturn and an oxygen sensor came up everytime.The oxygen sensor was replaced 3 times until my father found out she was topping off the gas tank.My father found out from a Vetronix rep he knows about this after calling him to ask about this problem.

Nope, I don't top off the fuel tank. The error is not the sensor, just rich fuel on banks 1 & 2. I had a mechanic tell me it was either the fuel pressure regulator or the front O2 sensors. Had the pressure checked and okay, and replaced the O2 sensor. Still have the rich fuel.

When they tested the fuel pressure regulator, did they take off the top half (plastic) of the intake manifold? They are prone to leaking fuel thru the vacuum line. To really inspect the fpr, you need to pull this hose and make sure fuel is not leaking.

If you drive it and let it set for 1/2 hour, how does it start? Right up or does it take longer than normal?

//2000CAYukon

It starts right up. Sometimes when it sits overnight or all day then it will start a little hard. I don't know how they tested the pressure regulator, I just dropped it off at a shop where I know a mechanic.