# A little help, please.....



## dmwz71 (Feb 5, 2010)

I have a 2003 Chevy Suburban Z71 4WD with about 211,000 miles on it. The engine light (when I pulled the codes, it was something to do with emission leaks, I don't recall the exact code, something like P0442....) has been coming on periodically for a long time now, so I have just been resetting it with my Super Chip programmer and going on until it came on again........Now, is it coming on much more frequently and when I reset it, it is not long at all until it comes on again. So, I decided to get it fixed correctly so I could get it inspected and registered. The shop I took it to put it on their analyzer and told me that it was a valve (?) or some such on the top of the gas tank, and that is where the emission leak was originating. I was told the only solution to the problem was replacing the gas tank, as that little valve could not be bought separately, that the only was to get it was with the tank. This just does not sound right to me. 

Anyone have any suggestions on an honest, no BS mechanic shop that could give me a second opinion on this matter? Preferably on the east/northeast side of Houston, as I live in Crosby, but I wouldn't mind going elsewhere for a dependable, honest mechanic. I seem to remember folks giving great reviews on 2Cool awhile back to a shop in Pearland (I think), but I have forgotten the guy's and shop's name. Any help would be appreciated. I need to get this taken care of by May or so, that's when my inspection expires. Thanks in advance!

Dennis


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## triton (Mar 3, 2005)

I have seen on some Chevy forums where replacing the fuel cap solved their issue as the seal was leaking. Maybe worth a try since a cap isn't that expensive.


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## snapperlicious (Aug 11, 2009)

http://www.aa1car.com/library/evap_system.htm


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## Cody C (May 15, 2009)

triton said:


> I have seen on some Chevy forums where replacing the fuel cap solved their issue as the seal was leaking. Maybe worth a try since a cap isn't that expensive.


Had this work before too

Sent from my iPhone using Tapatalk


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## Pocketfisherman (May 30, 2005)

The valve is likely the purge valve for the evaporative charcoal cannister that captures fumes and sends them back to the tank as liquid. Tracing the line from the evap cannister back to the tank will take you to the valve. Not sure of your GM, but on other brands it is part of the assembly that screws into the top of the tank and contains the fuel pump, fuel pickup, fuel gauge sender and wireharness for all of the above. Go to the RockAuto.com parts site, plug in your vehicle, go to the "Fuel/Air" section and look for Fuel Tank Sending Unit. It has the pickup and return fuel lines and associated valving. I'm sure it is not cheap, so I would try both a gas cap first, and also carefully inspect your evap cannister and associated tubing for cracks first.


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## Pocketfisherman (May 30, 2005)

If you end up having to replace the tank sending unit, order a gasket for it too! You will have to drop the fuel tank to replace it, so run it down as close to empty as you can first to make it easier.


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## ibtbone (Oct 7, 2013)

I doubt u need to replace the tank, find out what the code is for sure and post back. I work on chevys daily and can likely help if you havenmore info, by the way there in no valve on top of the tank that is part of the tank.


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## lx22f/c (Jun 19, 2009)

ibtbone said:


> I doubt u need to replace the tank, find out what the code is for sure and post back. I work on chevys daily and can likely help if you havenmore info, by the way there in no valve on top of the tank that is part of the tank.


X2
More than likely the part they are talking about is the canister vent valve. It is located beside the fuel tank. Very common failure and some are cheap as others are expensive and require re routing hose and adding a pigtail to the harness. Pm me if you need more info.


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## dmwz71 (Feb 5, 2010)

ibtbone said:


> I doubt u need to replace the tank, find out what the code is for sure and post back. I work on chevys daily and can likely help if you havenmore info, by the way there in no valve on top of the tank that is part of the tank.


Okay......after many doctor visits and cervical spine surgery, I am able to look into this again. I ran the codes yesterday and had three (3) codes:

1) P0420--Catalyst Sys Efficiency Below Threshold (bank....
2) P0430--Catalyst Sys Efficiency Below Threshold (bank 2)
3) P0442--Evap Emission Sys Leak Detected (small leak)

That is what the owners manual for my programmer/code reader says. Any further information/suggestions from the 2Cool braintrust?

Thanks,

Dennis

PS......I cleared and reset the codes yesterday, and this morning on the way to work, the light came on again (about 80 or so miles.)


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## GulfCoast1102 (Dec 30, 2013)

Those first 2 codes are typical of a bad catalytic converter. 

The 3rd one is the same one I have on my truck. I reset it, and it stays gone for about a month, then comes back. I read online that my truck's tank won't seal properly without an OEM gas cap. I went aftermarket before I read that. Haven't bothered buying an OEM yet to try it, but I probably will.


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## RogerTherk (Aug 24, 2011)

skitters


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## Viking48 (Jan 24, 2006)

Had the same problem on my 09 but the valve was behind the rear bumper.


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## ibtbone (Oct 7, 2013)

Need both cat converters replaced or for "off road" applications, wink, you can buy on line 2 simulators, plug into the harness, formthe 442 you need to smoke test it for an external leak, bit could be internal leak like purge valve.


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