newbie 2003 tahoe po171 and po174

[30backs]

hi im brand new to the forum I seem to be having trouble try to search this for some reason. I have 2003 5.3 4wd Tahoe with 127,000 miles on it. my engine light came on about two days ago when it 30 degrees for codes po171 and po174> when I search this it came up to be a lean bank so I cleaned my maf sensor and still no change. I am know leaning toward the fuel pump and wanted some opinions on it due to price of it. the only other thing besides he engine light is here recently it acts like it spins over a tad more than necessary but cranks fine and ideas?

 

[30backs]

Any one? I tested fuel pressure test and it was 48psi key on and 42psi running is this correct pressure for a flex 5.3? It also seem to idle funny when weather is around 30 degrees.

 

[MO Viet Vet]

Fuel pressure should be 50-55 psi. Rev up to 60 psi when WOT and then settle back when hold at cruise and not bleed off. Looks like pump and filter in your future. Could also cover the longer crank time before cold start.

 

[30backs]

I thought flex fuel was a lower psi?