Hey Folks,
This forum has been remarkably helpful since I bought my Hummer! Thanks in advance for the guidance .
Here goes: 2006 H3. Has 183,000 miles. New Jasper dropped in at 160,000. Three days ago, had a loss in power, shuddering at higher speeds, random misfire, intermittent rough idle (just replaced O2 upstream after a p0135), also a constant whine that sounds like the fuel pump. During acceleration the whine gets loud! Continues to throw a P0171. Within the last 6 months: new O2, cleaned TB, cleaned MAF ( which is only a year old), oil change with air filter change, new pcv hose. New t-stat with the Jasper. Oh, and I run pure, unadulterated gasoline through it.
I am stumped! Has anyone had a fuel pump on one of these go out with a lot of noise? I can't figure out the lean code or the noise. Help!

 

Could be related to your new O2 sensor but only if leaking, what brand? Is it installed correctly w/ no cross thread and tightened to spec?

A fuel pump is possible, but I would look at the easy things, like your air filter, intake leak including the PVC hose at the rear to the valve cover port, clean the MAF with MAF cleaner only, check the intake manifold fasteners to make sure they are all tight (known issue with all the I5 vibration).

You might want to scan it live stream and see what the MAF is doing, might need a new one if it is under-reporting.

A fuel pump swap sucks because the fuel tank has to be dropped to do it.

 

Have someone do a pressure and volume test of the fuel pump. If there is not enough volume it could be starving the engine of fuel. Usually a fuel pump either works or it doesn't causing a no start, but anything is possible.