Running lean p0171 p0174

[22duece44]

I need help figuring out what is going on with my 09 gmc yukon xl 1500 denali 6.2l l9h
At first vehicle ran great. Next day driving on high way p0171 p0174 came on cleared drove and then p2272 came on. P2272 came on more than once. P0304 p0300 came on at 1 point i switch ign coil 4 with 6 ans never came back but p2272 keeps coming back. No vacuum leaks found maf, all wires coils and plugs changed fuel injectors changes after market idk previous owner changed all. And new oil pump.
when truck first starts its runs rough only on first cold start and smooth put. Mpg is 8 to 9 mph on high way at 60 mph or 70 mph. My alcohol content is high showong 70 percent was at 60 every time i fill up it goes up even when full tank and drive for an hour longnafter fill up. I did use 87 gas and not 91 i did not know it was suppose to get 91. No gas smell just runs lean no matter what. New air filter new oil change. If you can see anything wrong please give me any advise.

 

[BG1988]

a large leak the canister vent solenoid could be stuck open
what is the PSI for the Fuel rail? what does the sensor say for the fuel pump PSI

 

[Fless]

If you're running gasoline (100%, or E10 or E15) then you'll need to have a scanner and reset the alcohol percentage so the computer can recalculate it.

Typically gasoline has some ethanol in it (no more than 10% or 15% as marked on the pump, so E10 or E15). If your truck "thinks" it's using E85 (up to 85% ethanol) then its going to dump too much fuel into the combustion chambers and cause rough running, excess fuel consumption, and possible fuel contaminating the oil.

 

[22duece44]

a large leak the vent solenoid could be stuck open

The vent solenoid on the engine or tank the vent solenoid on the engine has been replaced intake gaskets replaced I will smoke test it to verify

 

[22duece44]

If you're running gasoline (100%, or E10 or E15) then you'll need to have a scanner and reset the alcohol percentage so the computer can recalculate it.

Typically gasoline has some ethanol in it (no more than 10% or 15% as marked on the pump, so E10 or E15). If your truck "thinks" it's using E85 (up to 85% ethanol) then its going to dump too much fuel into the combustion chambers and cause rough running, excess fuel consumption, and possible fuel contaminating the oil.

 

[22duece44]

My scanner is zurich zr15s I can read the content levels but I can not reset it.

 

[22duece44]

a large leak the canister vent solenoid could be stuck open
what is the PSI for the Fuel rail? what does the sensor say for the fuel pump PSI

43 psi verified by guage its on the pictures psi is 43 psi to 44 psi idle and driving

 

[Fless]

Not concerned with fuel pressure at this point; that reading seems fine.

Get a shop with a scanner to reset the alcohol level. Less than a 10 minute job.

If you're near one of the Tech 2 owners that's on the linked list in this thread, you might be able to have one of them do it. In what part of the country are you?

Tech 2 Owners Map

There are quite a few members that have a Tech 2 and there are always people who wish they had one to use so I thought I would post this thread to try and help each other out. If you own a Tech 2 and would be willing to help out another forum member that might be local to you then post up your...

www.tahoeyukonforum.com

EDIT:

 

[Fless]

The vent solenoid on the engine or tank the vent solenoid on the engine has been replaced intake gaskets replaced I will smoke test it to verify

The "vent" solenoid is near the tank and vents the evap canister. The "purge" valve is on the engine and purges the vapors from the evap canister during an evap test cycle.

 

[22duece44]

The "vent" solenoid is near the tank and vents the evap canister. The "purge" valve is on the engine and purges the vapors from the evap canister during and evap test cycle.

Thanks I will check that next