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1999 STS
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45 Posts
Discussion Starter #1
Between some odds and ends repairs, and health issues I had not driven this car very much at all, and had not gotten the "Check Gas Cap" message before. The last thing I had done was to replace the fuel pump assembly, which was very problematic. So I know I should go back and make sure that there are no problems there, anyway about two days after changing the pump I got gas, and shortly after is when the check gas cap message came on. I reseated it, later cleared it, and it still comes on, btw no evap codes yet. This looks to be the oem cap with an o-ring, so is the o-ring replaceable, or not?
 

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02 Seville, 04 SRX
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1,347 Posts
I would start with a new cap. There may be an evap leak that you haven't found though. It is also possible that the neck is rotted out somewhere back where it can't be seen.
 

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1999 STS
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45 Posts
Discussion Starter #3
I would start with a new cap. There may be an evap leak that you haven't found though. It is also possible that the neck is rotted out somewhere back where it can't be seen.
Yeah I figure a new cap wouldn't be a problem especially if that is the original cap, and that brings me again to ask if the original cap uses an o-ring to seal, and is just the o-ring replaceable?
 

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92 Fleetwood 2dr cpe - FWD, 96 Seville SLS, 02 Seville
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957 Posts
Recheck your fuel pump installation. Bad seal or hose connection would cause a code like that to be thrown.
 

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1999 STS
Joined
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45 Posts
Discussion Starter #6
Recheck your fuel pump installation. Bad seal or hose connection would cause a code like that to be thrown.
Yep, that was my first thought on this as I did have a problem getting it out. I read all of the check gas cap post, and no one said anything about an o-ring in the gas cap, and that is what got me curious as to whether this cap is what I am supposed to have in it.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,451 Posts
Here's your EVAP setup. Any leak in the lines, tank seal, gas cap, charcoal canister will set the gas cap message. Even a rusted fuel fill pipe ........... and the green test port cap on the EVAP purge line next to the brake booster.

2002 EVAP.gif
 

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1999 STS
Joined
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45 Posts
Discussion Starter #8
Here's your EVAP setup. Any leak in the lines, tank seal, gas cap, charcoal canister will set the gas cap message. Even a rusted fuel fill pipe ........... and the green test port cap on the EVAP purge line next to the brake booster.

View attachment 582136
I've gone over the system a bit, and have seen no issues such as rust, bad lines and so on. Like I said in the beginning I think it is connected to the fuel pump replacement, I could not get a new lock ring at the time, and it took a bit of straightening on the old one, so that is an easy fix. Today I had no Check Gas Cap message lol so we will see what happens. ;)
 
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