EVAP system issue driving me nuts. - Chevy Colorado & GMC Canyon
 
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post #1 of 10 (permalink) Old 10-07-2016, 08:59 PM Thread Starter
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EVAP system issue driving me nuts.

Hello everyone. I have been dealing with an evap failure ever since I replaced my fuel pump/sending unit. I now get a P0455 code and gas cap notification. I replaced both purge solenoids and the gas cap and still comes in. Pulled the tank again (getting pretty good at this) and double checked the orings on the poly evap lines. Replaced one small one because it felt a little loose. Still getting code and notification. Any ideas. Could the seal on the new fuel pump assembly not be seated correctly? I put silicone grease on the seal thinking it would be best but maybe not. Any ideas would be GREATLY appreciated. It is a 2004 Z71 I5 auto with 185,000 miles on it. Still runs great except for this. The only other thing is that it isn't as "snappy" when it starts after sitting overnight.


Thanks


Paul
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post #2 of 10 (permalink) Old 10-07-2016, 10:26 PM
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Did the pump assembly include the Fuel Tank Pressure Sensor or did you swap it over from the old pump? It's the part that the 3 pin connector attaches to. Might want to check the seal on it. You should be able to access it through the wheel well, after removing the liner.

When was the fuel filter last replaced?
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post #3 of 10 (permalink) Old 10-08-2016, 02:49 PM Thread Starter
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Thanks for replying Cart. It was a complete new sending/pump assembly. Fuel filter is less than 3 months old. I sometimes can pick up the odor of fuel vapors. Do you think it is possible that the tank pressure sensor is leaking around the seal?

Paul
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post #4 of 10 (permalink) Old 10-08-2016, 04:21 PM
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Well, it is possible, but if the pressure sensor was already installed I would suspect something else. Perhaps the connection of the fill tube at the tank, or the vent hose that goes from the tank to the fill tube. If it hasn't been replaced, the flex connector on the fill tube is probably brittle after 12 years. You could probably also check them through the wheel well.

Last edited by cart7881; 10-08-2016 at 04:41 PM.
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post #5 of 10 (permalink) Old 12-07-2016, 06:32 PM Thread Starter
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Hey all,


Ok. Still have the P0455 and now getting a P0442. I reset the codes and the P0442 hasn't come back in the last 24 hours or so. The code scanner says that a charcoal canister can cause both problems and that is the only part that I haven't replaced. I did replace the smaller evap line harness that is on top of the fuel tank since the orings felt a little loose. That was about 2 weeks before the P0442 code started. Just bought some 5/15 fuel hose, a barbet tee, and slid the hose up onto the one tank fitting, the fuel pump assembly, and the fuel filler line. Nice tight fit. Didn't even need clamps. I have replaced both purge valve solenoid and the vent valve solenoid. The vent valve solenoid was replaced with the "Hummer" part. MUCH less expensive. Same valve and connector, just didn't come with the hard plastic line and oring fittings. I just used rubber fuel line and hose clamps. Did all that about a month ago or so. Could the charcoal canister be causing these ongoing issues? Is there some kind of mechanical valve in the canister that could be faulty? It is original and the truck has 187,000 miles on it.


Thanks


Paul
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post #6 of 10 (permalink) Old 12-07-2016, 06:39 PM Thread Starter
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Hey all,


Ok. Still have the P0455 and now getting a P0442. I reset the codes and the P0442 hasn't come back in the last 24 hours or so. The code scanner says that a charcoal canister can cause both problems and that is the only part that I haven't replaced. I did replace the smaller evap line harness that is on top of the fuel tank since the orings felt a little loose. That was about 2 weeks before the P0442 code started. Just bought some 5/16 fuel hose, a barbed tee, and slid the hose up onto the one tank fitting, the fuel pump assembly, and the fuel filler line. Nice tight fit. Didn't even need clamps. I have replaced both purge valve solenoid and the vent valve solenoid. The vent valve solenoid was replaced with the "Hummer" part. MUCH less expensive. Same valve and connector, just didn't come with the hard plastic line and oring fittings. I just used rubber fuel line and hose clamps. Did all that about a month ago or so. Could the charcoal canister be causing these ongoing issues? Is there some kind of mechanical valve in the canister that could be faulty? It is original and the truck has 187,000 miles on it. I have some "smoke in a can" that is used for testing smoke detectors. Do you guys think that would be ok to use to smoke test the system? Maybe when the tank is on fumes next time spray some down the fuel filler tube and see where it might be coming out? Opinions GREATLY appreciated.


Thanks


Paul
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post #7 of 10 (permalink) Old 12-07-2016, 10:16 PM
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The EVAP canister is basically just a plastic box full of charcoal. No valves. The only way it would contribute to your problem would be if had a hole(s) in it. It could be a coincidence, but if the problem just started after you replaced the pump, I would continue to suspect something is not quite right with the pump installation. A lot of work, but maybe you will need to pull the pump back out and inspect the seal.
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post #8 of 10 (permalink) Old 12-07-2016, 10:54 PM Thread Starter
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Unhappy

Yeah. I thought about that too. Just didn't want to mess with the locking tabs on top of the tank any more than I have too. They were pretty rusted. I did clean them off pretty good then painted everything with Chassis Saver paint. Thanks Cart.
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post #9 of 10 (permalink) Old 12-08-2016, 01:04 AM
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You can always hook it up to a smoke machine. Be aware if you do that, the vent valve will have to be energized (closed). If you do not do close it you will be leaking smoke out of the vent and will be difficult to see where the system is leaking.

I would be rechecking the fuel pump to tank seal and installation since that was the last thing that you touched before you had the code. Also do NOT use silicone on anything associated with fuel. If any of it migrates into the system, it can cause oxygen sensor problems.

2005 White 2wd Z71 WT
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post #10 of 10 (permalink) Old 12-15-2016, 12:45 PM
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Do you have a factory tow package?
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