2000 GMC SIERRA EMISSIONS FAILED

MY "SERVICE ENGINE SOON" LIGHT HAS BEEN ON FOR AROUND THREE YEARS (TAPED A ST. ANTHONY MEDAL OVER IT) AND TRUCK HAS BEEN RUNNING PERFECT. THREE YEARS AGO I DID HAVE TEST RUN AND MECHANIC SAID SOMETHING WITH THE GAS CAP, HOWEVER, HE COULD NOT GET THE LIGHT TO GO OFF. FAST FORWARD, FLUNKED TEST BECAUSE OF CODES "PO440, EVAPORATIVE EMISSION SYSTEM" AND "PO449, EVAPORATIVE EMISSION SYSTEM VENT VALVE/SOLENOID CIRCUIT". BOUGHT GAS CAP, REPLACED VALVE CIRCUIT, THE LIGHT REFUSED TO GO OFF. THREE DIFFERENT PLACES TRIED TO USE THE LITTLE PLUG IN THINGS BUT THEY WOULD NOT TURN ON TO RESET COMPUTER. I WENT BACK TO EMISSIONS PLACE AND THEY REDID TEST SAME CODES, THEY SAID TO GO TO DEALER AND HAVE THEM RESET CODES, DEALER SAID THAT THE TRUCK DOES IT WITHIN 100 MILES AND TRUCK LIGHT WILL GO OFF. DROVE OVER 100MILES AND LIGHT STILL ON, I HAVE TO TAKE BACK TO MECHANIC WHO RAN OUT OF TIME AFTER TWO HOURS OF CHECKING FUSES AND STUFF. ANY HELP PLEASE, SINCE MECHANIC CHARGES BY THE HOUR..

Reply to
clemert
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Let me guess...every time you fill the fuel tank, you try and get every last drop you can in the vehicle...after the gas hose stops, you slowly add as much as you can until it's at the top of the filler tank.

You aren't the only person that does this...but it causes raw gas to get into your evaporative cannister where only fumes are supposed to go. Gasoline in the emission can screws up the system.

Secondly, please don't use all caps when you type...It's irritating to read.

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Advocate

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clemert

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Shep

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clemert

Reply to
Shep

To check for EVAP leaks there will be a light green colored cap with hoses connecting up to it, they are typically no larger than quarter inch in size and some vehicles will have multiple test ports of this type. This is the location or connecting port if you will where smoke/vapor and or vacuum is applied to the EVAP system, if a leak is suspected via code on the diagnostic computer then in some cases low vacuum is applied and has to maintain a certain level for a period of time. If a leak is detected then a tool that generates smoke/vapor "NON FLAMBLE" is pumped in at low pressure and you will quickly find the leak,some shops just jump right to this step and skip the vacuum, its well worth the shop charge since most mechanics using the tools of this type and training ASE certified should find and fix the leak within an hour or so plus parts....hehe. A competent NEW car dealership shop should have this equipment on hand since it is a common problem now a days. And if it cant be fixed just shoot it! :-)

Reply to
GERALD FISK

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