06 Chevy intermittent p0171 and p0174 codes

2006 Silverado . 5.3 L. Below is the freeze frame for most recent, using blue driver. Truck will sputter when the temperature outside is above 80, and fuel level below half a tank, in drive or neutral. Will not sputter in park or reverse, has a smooth idle. Afew weeks ago it started, I stopped at fuel station, filled up and problem stopped. It doesn't always through a code. I checked all the intake hookups with ether, cleaned mass air flow, new gas cap, new air filter, throttle position sensor, gas pedal.

I've heard possible intake gaskets but with specific scenario when vehicle acts up has me confused. I'm thinking fuel system, either dirty injectors or weak fuel pump, being it quit after a fueling while vehicle running. alas I don't know how to interpret the freeze frame data.

Any help appreciated.
~craig

Holy shit look at this fuel trims.... long term on both banks is buried and short term is almost there lol... no this is not s intake leak bc that freeze frame is at 2000 rpm under load and being bad.... both banks .... fuel delivery id say 100%% check ur fuel pressure... start the engine and rev it up high and watch for crazy drop outs

try pinching off ur brake booster hose and watch ur trim numbers. if no change it is quite possible you have clogged injectors on both banks .. although i dont think putting fuel in ur tank would help them possibilities . is that a returnless system ?

It really fits a fuel delivery issue, the fact it improved when the tank was filled with cool fresh fuel is a pointer, fuel pressure check would be a good move I would also look at the pump and filter . Because it dosen't occur in reverse or idle I would also closely examine the wiring harness to the injectors and ignition for any opens or shorts that might be caused by engine movement.

Definitely fuel delivery related, as others stated. Get a hold of a fuel pressure gauge and do some snaps in Park or some power braking in Drive. Watching the gauge during a WOT run would be even better.

Any possibility that the tank got filled with E85? 'Cause that'll definitely cause a fuel issue. :lol:

Currently running pressure test. Started with 55 psi. After 5 min at 58 psi.

It started again today, the cel went off since Friday. Started with air temp above 90 and fresh fuel didn't help. First time it happened with a full tank.

Pinched vacuum line coming from brake booster with no change in trim levels on live Scan.

Turned key off at 10 min and has 54 psi.

As for e85 fuel, I don't have a station within 75 miles that has that stuff.

Oh fuel filter to my looking and knowledge the model year has just the sock inside the tank attached to pump.

With engine running the gauge hops between 54 and 62 psi. At 2k rpm it goes between 48 and 56.
In drive with brake held the psi drops to 10psi at 1500 rpm.

Wverwolf wrote: With engine running the gauge hops between 54 and 62 psi. At 2k rpm it goes between 48 and 56.
In drive with brake held the psi drops to 10psi at 1500 rpm.

Check power and ground to the pump. If they are good put a pump in it

bruce.oliver wrote: Check power and ground to the pump. If they are good put a pump in it

What he said. :lol:

from your posted test results, i also agree. Don't 4 get 2 inspect for any sediment inside the tank and restricted supply line to the injector assembly .clean tank blow out fuel supply line if necessary

Thanks for info everyone. ordered a Delphi pump.

My only concern and the thing that keeps me wondering is the fact the problem is intermittent. Past two days I have not had an issue and my past dealings with fuel pumps has been either working or not, none of this running weak then running fine. All electrical connections look good, vacuum lines look good, connectors look good.

It can start sputtering and not throw a code, then next day do it again and throw a code. It's been a really good truck so far, one wheel bearing, one o2 sensor, gas cap, has only been my problems.

I had a suburban do the same thing a couple years ago. I ended up putting long test leads on pump power & ground so I could use my scope when driving until it acted up & found to be ground partially failing. Pump ground on that vehicle was on firewall. Cleaned firewall & installed new ground connector for cure. Luckily before tank removal.

Ok, thanks eveeyone, got the new pump in and it's working fine. I drained the fuel out of tank and replaced with cleaner fuel. Running fine. Will have to see if issue comes back in coming weeks. Old pump had a hole in the bottom of it allowing large debris to enter the bucket and get to the sock, the sock was completely covered with trash. If it happens again I'll check the ground and make sure it's secure and clean.

Once again, thank you everyone for helping me in diagnosing.
~craig

Great to hear! We'd love to hear back from you in the future, either way.

Ok, 2 tanks of fuel later and no hesitation when fuel gets low(around 1/4 tank), when air temp is hot, etc. No problems that it was having previously are present, *fingers crossed*.

Once again, thank you everyone for helping me in diagnosing.
~craig