About a month ago, my check engine light came on. It had came on a few weeks before, but turned off before I could get it scanned. As soon as it turned on this time, I took it to the closest Advanced Auto Parts and had them scan it. It threw a P0171 code - engine bank 1 too lean. I sat in my car browsing Google for about ten minutes to find cheap potential fixes and settled on trying to clean the MAF sensor. I went back inside, but their stock of MAF cleaner was gone, so I bought the required security torx bit to remove the sensor and drove over to a local parts store up the road. They had a bountiful supply of MAF cleaner, so I bought a can and headed home. I'd like to say that cleaning the MAF sensor was the easiest job I've done on my Bonneville since I got it back in May. When I got home, the cleaning commenced. It didn't look terribly dirty, but I figured it couldn't hurt to spray it down anyways. After a few engine startups, the code went away. In between then and this week, I unsuccessfully tried to replace the fuel sender arm (I replaced it, but the fuel gauge was 100% inaccurate afterwards and would only read full and empty). This week, the light came back on so I ran it over to Advanced. They didn't write down the codes for me this time, but he said it was throwing out engine too lean, fuel pump, and fuel sender errors. I've started to wonder if a new fuel pump, which would be guaranteed to fix 2/3 problems, could also possibly fix the too lean problem? I'm not too technically advanced so I really don't know if the fuel pump would have any play in the engine running lean. If the fuel pump wouldn't solve it, what else could I try? Regardless of whether the fuel pump would fix the lean error or not, I bought one off of rockauto today - I don't want to mess more with the sender and my car is almost to 180,000 miles, so I don't expect the factory pump to last much longer anyways.

you can hook a fuel pressure gauge up to the fuel rail and see if it is low. I know on an SSEI it should have around 52 psi with the key on and engine off and about 44 psi at an idle. done know if there is a difference in an SLE.

I believe our cars only measure fuel mixture on one bank anyways (in downpipe after both manifolds collect), so you are probably lean on both banks.

Amazon.com has a 20% coupon on the ac delco fuel pump i just bought.

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