**SIGH** On to the next delima: lean problems!
 

so now im getting a p0171 and p0174 code thrown at me on the 02 burb. i see there are numerous possibilities of what this could be.

i've changed out the o2 sensor within the past 18 months so im not sold its that. i also see it could have something to do with the fuel pump/filter/etc. i will say that here recently if we let the gas get down to less then a quarter of a tank it seems harder and harder to start. to the point of 2 or 3 times last year it wouldn't start at all unless i put more gas in it.

before i go and drop a lot of money into dropping the tank and replacing the pump, is there anything else that i should try before i hand it off to my mechanic?

Re: **SIGH** On to the next delima: lean problems!
 

Vacuum leak or incorrect readings from maf sensor, either from not working correctly or being dirty.

Re: **SIGH** On to the next delima: lean problems!
 

is it suggested to clean, or replace the maf?

Re: **SIGH** On to the next delima: lean problems!
 

Intake manifold gaskets

Re: **SIGH** On to the next delima: lean problems!
 

yeah thats another thing i've seen pop up was the gaskets. it sucks there are so many things it could be. i don't have the time/money to be throwing at things that don't fix it :)

Re: **SIGH** On to the next delima: lean problems!
 

If its dirty it will give incorrect readings. I would try cleaning it first. 95% of the ones I see with both banks lean is usually dirty maf or vacuum leak.

Re: **SIGH** On to the next delima: lean problems!
 

cool. i'll look into doing that. anything recommended/not recommended to clean it with?

Re: **SIGH** On to the next delima: lean problems!
 

Had the same problem on my 03 sierra. Changed the intake gaskets cleanend the throttle body, and it runs good as new..

Re: **SIGH** On to the next delima: lean problems!
 

Advance auto sell MAF cleaner made by CDC..... thats what i did

Re: **SIGH** On to the next delima: lean problems!
 

Change the fuel filter.
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Re: **SIGH** On to the next delima: lean problems!
 

I had a truck at work with the exact same codes... I found a vacuum leak at the intake .. used brake clean to find the vacuum leak.. customer didnt approve the intake gaskets but I had snugged down the bolts and it really helped ... but that was just a band aid ... yours may be different ... another truck with the same codes had a tear after the MAF sensor before the throttle body... sometimes theyre easy sometimes not so easy