lean codes = fuel filter replacement?

[CaptTrevStarr]

hey folks
been have a dtc light come on all the time now...clear it and bout 50 miles it come back on...p0171/p0174...obviously they are lean codes...had been speaking with some ase certified mechanics and they say to change the fuel filter and check for vacuum leaks...well there are no vacuum leaks...and http://www.ls1truck.com/forums/site-...rum-rules.html i just spent an hour lookin for my damn fuel filter only to come back on here to find out that my year they went returnless and the filter is in the tank itself...soooo what are the odds of me having to drop the tank or remove the bed to swap out a new pump/filter assembly....04 silverado lts hi flo cats flowmaster exhaust..aftermarket mass kn intake..

thank you in advance

trevor

[CaptTrevStarr]

ok dont know why i have a link in my post??

[farmtruc]

Instead of pulling the tank assembly, check fuel pressure, if pressure is fine, it's not the filter.

Put a stock maf back on the truck and see if that fixes it. Even though it's tuned for, I have seen them still cause lean codes.

O2's, vac leaks, low fuel pressure, maf will cause lean codes.

The link is there cause you probably said a bad word, lol.

[CaptTrevStarr]

thank you.....just did all 4 o2s last month, and as of 10 mins ago the stock maf is back in.....check vac leaks this afternoon but didnt find any...any pointers on where to look...i checked the intake mani and brake booster...will check fuel pressure tomorrow...

thank you allen

Trevor

[farmtruc]

Most common place vac leaks occurr

Between Maf and throttle body
Vac caps that have split from being old
Booster
Hose from valve cover to throttle body
Intake manifold

Best thing to do is get ahold of a smoke machine.

See if the code clears now that stock Maf is on

[CaptTrevStarr]

with the stock maf in there, ive yet to have a cel come on..gonna drive it around a bit more to see what happens

thanks allen, i appreciate it

Trevor

[farmtruc]

alright, good to hear!!!

[RUFFNECK]

I had the same codes cuz my intake manifold gaskets were leaking. I couldn't check it by testing but when I took off the old ones, you could see where it was blowing by and leaking. So now I just change them like every 50k, it only takes an hour. Just a thought.