Question about 2005 Chevrolet Tahoe
Posted by Anonymous on
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Posted on Jan 02, 2017
its above ur fuel tank from what i kno of but it could be ur canister or just a short in the wire to ur solenoid
Posted on Jan 17, 2009
You are right. You need the vent valve not the purge valve. The vent valve is a dealer item. Also this is a common problem and GM has released a bulletin on this that involves moving the location of the valve and running some new lines. It comes as a kit from GM, and it costs about a 100 bucks.
Posted on Dec 02, 2010
SOURCE: 1997 malibu / I had faulty code po440 . I Replaced Purge valve behind engine, canister valve solenoid, gascap from dealer, charcoal canister, smoke test. 1 week later check engine light on again wit
Diagnostib Test Code (DTC) P0440 is defined by SAE J2012 simply as "Evaporative Emission System".
This code is what I call a "catch-all" code for the evap system. This is the code that sets when all the other EVAP codes do not apply and there is a malfunction detected in the EVAP system.
It is not really hard to diagnose this code if you have the correct equipment and understand how the EVAP system operates.
How DTC P0440 sets:
The system is tested when there are no electrical problems with the Purge Control Solenoid Valve (PCSV) or Canister Vent Solenoid Valve (CVSV) circuits and the Fuel Tank Pressure (FTP) sensor voltage is within the operating parameters. The Powertrain Control Module (PCM) commands the CVSV to close and the PCSV to open and apply vacuum. It then looks for a change in the FTP voltage to indicate that there is a vacuum being drawn on the fuel tank. If there is no change, DTC P0440 sets.
If there is a change in FTP voltage, the PCM draws the vacuum to a predetermined set point and closes the PCSV (leaving the CVSV also closed) and looks for decay in the vacuum in the tank as evidenced by the FTP voltage. If the predetermined set point cannot be reached, DTC P0440 sets. If the set point is reached and the decay is faster than allowed over a predetermined time period, DTC P0440 sets.
It should also be noted that the monitor for this code is a "type B" DTC, meaning that it must fail on two successive drive cycles before it will turn the check engine light on. So, if it fails on the current drive cycle, then the conditions for running the monitor are not met on the next drive cycle, the code will not set on the second or third drive cycles. All conditions must be met and the monitor must fail two drive cycles in a row. This explains why it may take a week or two before the check engine light comes back on.
This code is very easy to diagnose using a scan tool that is capable of performing "purge and seal" tests and graphing the FTP voltage over time. The technician can actually "see" the vacuum being drawn on the fuel tank and the vacuum decay by doing it this way. Repairs can be verified this way without having to drive the vehicle several times to get the EVAP monitor to run.
By running the evap purge/seal function on the scan tool and using hose clamping pliers, different parts of the system can be checked by clamping off the hoses that connect the components and watching the FTP voltage graph. If there is no change in the FTP voltage when the system is commanded to purge, a vaccum gauge should be used to verify that the purge solenoid is actually working and that vacuum is being applied to the rear of the vehicle There could be leaks in the line between the purge solenoid and the canister.
For an example of how this works:
Possible rust holes in the filler neck and/or a defective fuel cap can be determined if there is no change in the FTP sensor voltage or rapid decay upon the initial test that goes away when the filler tube hose is clamped off between the filler tube and the fuel tank. A sticking CVSV can be determined in the same fashion by clamping off the hose between the charcoal canister and the CVSV.
Holes in the hoses themselves can also be diagnosed the same way by disconnecting them from the vacuum source end and plugging the source tube. Example, remove the vent hose from the canister and plug the hole in the canister. If the problem goes away, it is either the hose leaking or the CVSV leaking. So, reconnecting the hose to the canister and disconnecting it from the CVSV and plugging the end of the hose will tell you if it is the hose or a sticking CVSV.
This may sound really involved, but it is very easy to diagnose this way once you know how.
Posted on May 11, 2012
If you go to autozone dot com and make a free account and put in the make, model and year you can access the free repair guides.
Posted on Apr 04, 2013
Tips for a great answer:
Oct 05, 2015 | 2004 Kia Sorento
Push down, while pulling up slightly in order the disengage the tube.
Disconnect the EVAP canister purge solenoid electrical connector (1).
Remove the EVAP canister purge solenoid bolt (2). Remove the EVAP canister purge solenoid (3) and insulator (1).
Sep 19, 2015 | Cars & Trucks
An EVAP canister, vent hose, or vent solenoid valve that has restricted flow may cause this DTC to set. Using a purge solenoid command with a scan tool will allow vacuum to be applied to the system instead of pressure. With the engine running, the EVAP canister vent solenoid valve open, and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than 5 inches H2O.
An EVAP canister filter that is restricted can cause this DTC to set. Refer to Evaporative Emission Canister Replacement .
Disconnecting one component at a time while the EVAP system is under flow will help to pinpoint a restriction in the system
Do you have a scan tool that reads data PID'S ?
Your FTP - fuel tank pressure sensor could be at fault !
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