2003 5.3L Yukon O2 Error Codes

[lgrouper03]

Today was driving from MO to TX. Stopped in AR to let the kids use the bathroom. Turned off the car like usual. Came back out tried to start, it ran very rough, very low idle (~400 rpm) then died after maybe 5-7 seconds. Tried to start twice more. Same thing but died quicker, after maybe 2-3 seconds. On those latter 2 attempts, I tried fluttering the pedal a bit when it was running for those 2-3 seconds, wondering if that would help like the old carburetors, no help, it died. So I sat there a bit (maybe a minute) thinking what to do, what could be wrong. I tried a 4th time, this time it started up normal. We drove off. I thought all was normal (though thinking that was strange behavior at the gas station). Then it came time to pass someone and, trans kicked down as usual, but engine flatlined at 4K rpm. So I canceled the pass maneuver and pulled back in behind the truck. Now I'm really starting to wonder what is going on. No check engine light thus far. As long as I keep my foot out of it, everything seems fine. Later, I had cruise on, and we went up a large hill. When the trans kicked down to maintain speed, then the trouble started again. We were going about 80 mph, but as soon as the trans kicked down to maintain that speed up the hill, we lost about 5mph, engine surging, and then the check engine light flashed a few times and went off. I had quickly turned off cruise and got out of the gas and then it settled back down. Got home and pulled codes (no check engine light by the way): P0131, P0137, P0151, P0157, and P0300. So if I take these codes literally then all of my O2 sensors are bad correct? Somehow I don't buy that. Anyone have any thoughts on this? By the way, after getting home and letting it sit a while, I went back out and bought some gas. Car started and ran fine. I will say that during my test drive, I got in it thru 1st and 2nd gear, noticed some detonation in 2nd that I am not used to hearing. I also recalled hearing that earlier in the day when passing someone up in the Ozarks, didn't think much of it though, seemed to be running OK at that time. I appreciate the help in advance.

 

[SLCHOE]

Sounds like a bad fuel pump. Low voltage on O2's means Lean. P0300 is random multiple misfire. All of those codes along with the symptoms you described could be caused by a failing fuel pump. Put a fuel pressure gauge on it and see what readings you get at idle and power braking it (putting a load on the engine) when the engine is up to temp.

 

[lgrouper03]

OK this thought crossed my mind, but just needed a more informed person to weigh in. It will be 2-3 weeks before I get to tackle this project (assuming I end up replacing the pump). But when I do, I will report back the results. Thank you!