Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
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Both of those codes lead towards excessing vacuum in the tank and are usually caused by a stuck open purge valve although you say you already replaced that. Normally there will be little or no vacuum at the purge valve when disconnecting the hose that leads to the tank. With the electrical connector disconnected the solenoid should be closed and no vacuum. With it connected there may be a slight bit of vacuum depending on temp and engine load, etc. The solenoid is pulse width controlled by the pcm and if commanded on at idle at all... will only be in the 10% range.
What I would suggest is reading the fuel tank pressure sensor reading with a scan tool with the fuel cap off and seeing if there it is reading a vacuum. We may have an issue with the fuel tank pressure sensor itself which is on top of the tank in the fuel tank meter assembly. Do you have access to a fully functional scan tool that can command the solenoids off and on?
I have a scan tool that can read the codes but I am not sure if it can command the solenoids off and on. My guess would be no. It is a cheap scanner, Toptek 180 model. Just to clarify there is no vacuum with the electrical connection disconnected on the purge valve and no vacuum with it connected.
When I opened the fuel cap yesterday, I noticed a puff of pressure so I am guessing the fuel tank pressure is in fact high. Haven't taken a second look at this since I was assuming the solenoid was stuck closed and I was not getting any vacuum on the system.
It would be the correct way to diagnose it (with a scan tool). You may try visually inspecting the vent solenoid for a restriction. I've seen them restricted with anything from dust to insect nests.
I couldn't tell without seeing it.
The best pictures I could find are below. There are a couple different setups...
Ok, in the top picture moving from top to bottom, vent valve, purge valve, fuel tank. correct? If so I will have to get a better scan tool and checdk lines for pluggage.
I can't quite recall without seeing it however the top picture should show it pretty well
I'll be away for a while doing Valentines day duty. :)
It will not be today and probably not for a week or so.
thanks, how do i get back to you in the future so i don't have to start over. i am new to this site.