P0172, P0175 too rich, 07 6.2 about to throw in the towel

[chucksrt]

I have a 07 Yukon denali xl with 120,000 miles on it. I started getting a check engine light a month or two ago. I researched it and replaced items that are common to causing this issue. I didn't care if it was the fault or not because of the miles i just figured the new parts would help it regardless. I started by replacing the EVAP purge solenoid. That actually seemed to help me fill the tank to full better? I then replaced the mass air flow sensor, again, i have cleaned it but thought a new one wouldn't hurt. Then i replaced the MAP sensor. I know that they can be a common point of failure. It seemed to run better but still had the C.E.L. i took it to a friends shop and he wasn't much help. He pretty much looked it up on Mitchell and said it sounds like the fuel injectors are bad. I bought a used set of injectors and sent then to FIC to be cleaned and flow tested. I received them yesterday and installed them and on my maiden voyage the codes returned in pending. I am at a loss!? I am going to take it to GMC to look at ir bur i do not know what else to check. Any thoughts or have you run into a similar issue where something else fixed it?

 

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[chucksrt]

I do not see a status for the fuel tank pressure sensor on my scantool. So i can not tell if it is working or not

 

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[wildcatter]

I agree, forget about the stabilitrack for now and sort out the problems at the tank.Did you find the source of the fumes? get a scantool on it and find out what codes are still there.

[newdude]

Just for full disclosure i wanted to add a list of odd issues it has had.

It sometimes would crank and not start, very intermediate

Just last week it started cranking excessively long and stumbled when it finally started, until it idled itself smooth.

My fuel tank is hard to fill to full? I can fill it and the nozzle shuts off and still be able to ad 4-5 more gallons after if i let it sit for a minute.

Idle has a ever so slight stumble? I have installed new plugs and magnecore wires within the last 10,000 miles and there are no cylinder misfires. That is all i can think of at the time although i am sure there is other stuff. Lol

 

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Fuel tank pressure sensor? Seen quite a few of those go bad. Can't say they've triggered rich codes though for sure.

[wildcatter]

Every plugged vent I've worked on showed no signs of fuel starvation to the engine.i believe the vent in the cap would prevent that from happening.

[chucksrt]

GM doesn't have a fuel pump listed for a non flex fuel vehicle. Does anyone know if they are the same pump as the flex fuel

 

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[chucksrt]

UPDATE!!!!! I replaced tje fuel pump and it seems my check engine lights have stayed out. I don't know if it was something with the pressure sensor or the fuel pump itself but it has been trouble free for nearly a whole tank.

 

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[chucksrt]

I was able to replace the vent tube assembly. Went fairly smooth. When i drove it i noticed that the service stabilitrack light and check engine lights were out. They were pretty consistant before. The truck did hesitate to start however. But it did. Drove it a couple of times and sure enough the service stabilitrack light came on a couple of times. I did not recheck the codes but i am sure it is still for running rich. After driving it the check engine light has stayed out although i know there are pending codes. But start up is tough. I am going to buy a fuel pressure guage tomorrow hopefully. It seems like the fuel is bleeding down, but i know the injectors were just done and tested so i am sure the only other piece is the fuel pump. From what i have seen, it looks like tje regulator is built into it as well as the fuel tank pressure sensor. I cant imagine how that could be related to the P0172, P0175 but i hope it is for my pockets sake!

 

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[wildcatter]

Have your filling issues gone away?

[Jsdirt]

I think I'm thinking of a different vent than you are talking about. You must be talking about the vent that allows you to fill up without gas puking out of the filler neck. I was thinking of the vent on the charcoal canister that lets the tank breathe (in only), or cap, if that's where they put it now.

[Jsdirt]

Don't go replacing stuff unless your 100% sure of the problem. I had to re-read alot of this, since I've forgotten the chain of events here ...

 

You very well may have fixed the rich codes with the EVAP purge valve replacement. You need to see EXACTLY what pending codes exist. Stabilitrak issues are more than likely from an ABS sensor issue, or steering sensor issue ... but that's not your original problem - need to focus on that first. Need to verify a fix (or not) with scan tool.

 

If the check engine light isn't on, then there are no codes in the system. Need to get in there and check for pending codes, if any - just because the Stabilitrak light is on doesn't mean there are pending codes for anything else but that system itself.

[tbarn]

I believe the only GM vehicles that have fuel pressure sensors are the ones with a high pressure engine mounted pump. They usually have high and low pressure sensors.

[chucksrt]

I have a scantool comming tomorrow so i can read the freeze frame data and live data. Hopefully that can help narrow it down. It seems to idle worst and worst as the days go on. Almost like it has a weak fuel pump.

 

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[chucksrt]

The P0172,P0175 codes did come back. I don't know if the two issues are connected or not but the extended crank seems to have gotten better, not good but better since replacing the vent valve assy. It may be a placebo effect? If I am understanding it right there are only two things that could cause the extended crank, leaking injectors ( which were just cleaned and flow tested) or the fuel pump. As for the codes i am completely at a loss as to ehat is causing them.

 

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[chucksrt]

I agree, forget about the stabilitrack for now and sort out the problems at the tank.Did you find the source of the fumes? get a scantool on it and find out what codes are still there.

I have not smelled the fumes again since that one time.

 

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[Jsdirt]

Regulator is in the tank on this one. Single line - returnless system, non-DI. The data here just confirms the rich condition, but doesn't tell us much else.

 

Is this a flex vehicle? I don't see it in the parameters, so I don't know if that's the fault of the tool, or that the truck isn't flex ...