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04 chevy trailblazer, gas tank airlocked, possible evap failure. need help


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craigg
New User

Jul 28, 2016, 8:00 PM

Post #1 of 8 (1058 views)
04 chevy trailblazer, gas tank airlocked, possible evap failure. need help Sign In

Hello,

I'm having a bit of a problem filling the gas tank and I suspect it is due to a failure in the evap system. I will describe the problem as best I can.

When the problem started I could only get about 3/8 of a tank of gas in the truck and I could only ever pump a few cents worth of gas at a time before the gas backed up and triggered the pump to stop. After a few months of that it has now gotten to the point that I can only get about half a gallon in it at the time. Needless to say I stop at every gas station I come across.

My first guess is that it is the charcoal canister but I do not have enough money to start replacing stuff until I get it. I really need to know for sure what is wrong before I buy stuff to fix it.

The vehicle is an 04 trailblazer LS 4x4


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 29, 2016, 4:20 AM

Post #2 of 8 (1036 views)
Re: 04 chevy trailblazer, gas tank airlocked, possible evap failure. need help Sign In

It has a vent control solenoid that controls the venting through the charcoal canister. That valve may be stuck in the closed position or you may just have a restriction somewhere in the filler line.

You may be able to temporarily disconnect the vent line into the canister to test fill the tank to determine if the vent valve is actually the problem. You cannot leave it disconnected.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



kev2
Veteran
kev2 profile image

Jul 29, 2016, 6:00 AM

Post #3 of 8 (1027 views)
Re: 04 chevy trailblazer, gas tank airlocked, possible evap failure. need help Sign In

Agree that sounds like classic VENT VALVE issue.
Did you scan for codes ? Yes even with light out.


craigg
New User

Jul 29, 2016, 8:20 AM

Post #4 of 8 (1018 views)
Re: 04 chevy trailblazer, gas tank airlocked, possible evap failure. need help Sign In

No I haven't taken it to get the codes scanned. Would the vent valve produce a code? I would have just enough gas to get to the parts store to check it. Do you know where the vent valve would be on this vehicle? If I got it to the parts store I would have to fix it on site or I'd be stranded. That's why I feel it is important to see if I can figure out what it is before I got. To know if they will have the part and if I will be able to fix it myself there at the parts store.

Would disconnecting a hose bypass the vent valve so I can at least fill the tank up half way and if so where might this hose be at on this vehicle? I looked under the back below the gas cap and I see what I think is the charcoal canister just above the spare tire. It is a rectangle thing about half the size of a cinder block.


craigg
New User

Jul 29, 2016, 11:32 AM

Post #5 of 8 (1002 views)
Re: 04 chevy trailblazer, gas tank airlocked, possible evap failure. need help Sign In

ok, it took everything i had to get under the truck and disconnect the hose to the vent valve. Went to the gas station and it filled right up. I will have to get the truck in the air to fix replace the valve. Would it hurt much if it were disconnected upwards of a week until my mechanic can get me into his shop?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 29, 2016, 4:20 PM

Post #6 of 8 (989 views)
Re: 04 chevy trailblazer, gas tank airlocked, possible evap failure. need help Sign In

There is no reason to leave it disconnected. You have a full tank of gas.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



craigg
New User

Jul 29, 2016, 4:48 PM

Post #7 of 8 (984 views)
Re: 04 chevy trailblazer, gas tank airlocked, possible evap failure. need help Sign In

Understood. But I do not believe I can get up under there to hook at back up. It was really all I could do to disconnect it. It took me about 1 hours to do that.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 29, 2016, 4:50 PM

Post #8 of 8 (981 views)
Re: 04 chevy trailblazer, gas tank airlocked, possible evap failure. need help Sign In

It will probably cause a check engine light but you can have the code cleared after repairing it.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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