Out of the blue, my Jimmy will not run. It barely idles, very rough, and dies as soon as you touch the gas pedal.

There's also a small whine when you first put it in accessory which has always been there (I assume it's related to the fuel system, a pump or something), but now sounds rough and grating.

The codes all suggest it's running way too lean, so I figured it was a fuel delivery problem, but after reading through various threads here related to the codes, I wonder if maybe it's a sensor or PCV problem instead.

Has anyone had something similar happen, especially with similar error codes?

 

Sounds like a fuel pump to me with the whine changing to grating sound. You can get a loaner fuel pump gauge from autozone, advance auto parts, etc with deposit to check things out. See link at top of this forum for checking fuel pressure.

Good luck

 

All three DTC's relate to problems with the B2S1 oxygen sensor, (front sensor, passenger side). A vacuum leak in the PCV system would set lean codes, (P0171 & P0174) for BOTH oxygen sensors. All of the symptoms you describe, point to a fuel delivery issue, (low fuel pressure) possibly a failing fuel pump. As Les mentioned, check that first, here's the link: https://blazerforum.com/forum/2nd-ge...eakdown-88305/ Post all 4 readings and we can analyze them for you.


Once that's taken care of, we can help you diagnose the oxygen sensor DTC's.

 

Thank you for the suggestions! I will take a look this weekend. I wonder, though, is the fuel pump you're talking about the one in the gas tank? Because that went out a few years back and was replaced. And this grating sound seems to be coming from the engine compartment.

 

Hmmmm.... Grating sound must be something else. Can you identify? Probably unrelated to your no-start but who knows. Still test fuel pressure please.

 

It appears the grating is more of a strained whine, and isn't coming from the engine at all. It just sounds like that when I'm in the cab. The pressure tester maxed out at 10 psi. Sigh. That sounds like a fuel problem, then.

 

Post #3 above has a link that explains how to test fuel pressure and leakdown. If it in fact needs a pump, use AC Delco or Delphi only!

 

I read through that and did the pressure test. It was at about 10. I have a new filter now that will get put on tomorrow morning. If that doesn't help, it's going to the shop. I replaced the pump with help from friends probably 5 years ago, and it was a huge pain in the ***.