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My odyssey to fix a fuel fill issue

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Old 09-16-2018, 11:09 PM
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My odyssey to fix a fuel fill issue

Hi All,

Figured I'd post a synopsis of the steps I went through in diagnosing and fixing a fuel fill issue I had with my '04 996TT, so others don't have to go through all the things a tried. Kudos to LQQK for the help in getting this fixed!

Background - Got the car about 3 months ago. It was my first 996TT, and right away noticed that the gas pump would shut off very quickly after starting to pump gas. It was like nothing could get down the filler neck. Startled, I researched this forum and others, and found plenty of people had similar issues. Most said to try turning the handle upside down, which I tried, but didn't make any difference.

Next, I kept seeing people replace the fuel fill vent valve on the filler neck. Pelican had a good article detailing how to replace it, so I figured if it's common enough for them to make an article out of it, I could give it a try. I ordered a replacement valve, and in the mean time, I discovered that if I used a small screwdriver to push down on the plastic tab to the right of the gas cap during filling, I could get fuel in SLOWLY. Like 10 min+ to fill it up. That made me think that doing that let some vapors vent out and let fuel in. I did that trick for about 2 weeks until i had time to replace the fuel vent valve.

Got the fuel fill vent valve replaced finally, and, unfortunately, the fill problem was exactly the same! Damn. This wasn't going to be easy, so back to Google it was. I needed a diagram of the whole ORVR system so i could what other valve are involved in venting the tank vapors. I found a PDF of the GT3 ORVR system (attached), and studied the hell out of it, making notes as to how I though the vapors flow during fill up. I drew a copy and made notes as to the behavior of the valves, and honed in the "ORVR Valve", which comes directly off the tank. This valve is controlled by the same circuit that activates the "Fresh Air Valve/Shut off valve" which is located by the front right headlight. I had noticed that when I pushed on the metal flap at the top of the fuel filler neck, I heard a loud click from that valve, so I figured it was working OK. So back to the ORVR valve it was, since it sits before the Fresh Air valve and must be blocked or broken.

Now, at least on the '04 996TT, the ORVR is in the worst possible spot to replace. I mean, the worst (to me at least ) It sits on top of the fuel tank, directly under the carpet (and metal) where my 4 disc CD changer had been. I knew I'd have to lower the tank at least, if not remove it completely out of the car to get to the valve. I had tried getting at it from the wheel-well (impossible), and despite even lowering the tank so it sat on the front diff, I could just barely get my finger on it from the access panel under the battery. Before going further, I needed to absolutely be sure the valve was broken, so I disconnected the wires leading to it via the connector which sits under the battery tray, next to the tank pressure sensor. Applying 12V to the pins, I couldn't hear or feel anything from the valve. Dead. At this point I was sure the valve was broken. Interestingly, the coil resistance was the same as the replacement, so that's not a good indicator of functionality.

So, we made the call to drill a 4" hole directly above where the valve sits, through the metal panel under where the CD changer had sit (see picture). Not an easy call to make, but since the only other way was to drop the whole front diff and tank, i knew I'd be looking at some serious labor bill if I took it to a shop. A quick job with the holesaw, and we were able to easily replace the valve. Upon testing the system by manually pushing the metal flap in the fuel filler neck up, I felt the valve actuating! I'll be getting a bung to plug the hole in the future, but once the carpet is back on, you can't tell anything was done.

Took it the to the gas station, and was rewarded with the most boring fill up ever Hopefully this helps someone with hard to fix fuel fill issues!
 
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Last edited by benschwe; 09-16-2018 at 11:12 PM.
  #2  
Old 09-16-2018, 11:53 PM
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Yikes! That all I can say - I hope I don't get that one.
 
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Old 09-17-2018, 10:48 AM
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I like your persistence and process for finding (and fixing) the problem...troubleshooting steps can be quite helpful for future users...you might add to check the fuse as an initial step for diagnosis before drilling holes that is. Glad you got it fixed, hope that doesn't happen to me either.
 
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Old 09-17-2018, 12:52 PM
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I have this same exact problem. The filling issue is intermittent. Some weeks I get a normal fill, others I get the 15 minutes at the pump. I now have an error code indicating a pressure problem, so the time is nigh to fix. Thanks for posting, I'll be doing this soon. Hopefully without the hole saw.
 
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Old 09-17-2018, 02:29 PM
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Can you add some pics of the hole, location, etc.

Originally Posted by benschwe View Post
Hi All,

Figured I'd post a synopsis of the steps I went through in diagnosing and fixing a fuel fill issue I had with my '04 996TT, so others don't have to go through all the things a tried. Kudos to LQQK for the help in getting this fixed!

Background - Got the car about 3 months ago. It was my first 996TT, and right away noticed that the gas pump would shut off very quickly after starting to pump gas. It was like nothing could get down the filler neck. Startled, I researched this forum and others, and found plenty of people had similar issues. Most said to try turning the handle upside down, which I tried, but didn't make any difference.

Next, I kept seeing people replace the fuel fill vent valve on the filler neck. Pelican had a good article detailing how to replace it, so I figured if it's common enough for them to make an article out of it, I could give it a try. I ordered a replacement valve, and in the mean time, I discovered that if I used a small screwdriver to push down on the plastic tab to the right of the gas cap during filling, I could get fuel in SLOWLY. Like 10 min+ to fill it up. That made me think that doing that let some vapors vent out and let fuel in. I did that trick for about 2 weeks until i had time to replace the fuel vent valve.

Got the fuel fill vent valve replaced finally, and, unfortunately, the fill problem was exactly the same! Damn. This wasn't going to be easy, so back to Google it was. I needed a diagram of the whole ORVR system so i could what other valve are involved in venting the tank vapors. I found a PDF of the GT3 ORVR system (attached), and studied the hell out of it, making notes as to how I though the vapors flow during fill up. I drew a copy and made notes as to the behavior of the valves, and honed in the "ORVR Valve", which comes directly off the tank. This valve is controlled by the same circuit that activates the "Fresh Air Valve/Shut off valve" which is located by the front right headlight. I had noticed that when I pushed on the metal flap at the top of the fuel filler neck, I heard a loud click from that valve, so I figured it was working OK. So back to the ORVR valve it was, since it sits before the Fresh Air valve and must be blocked or broken.

Now, at least on the '04 996TT, the ORVR is in the worst possible spot to replace. I mean, the worst (to me at least ) It sits on top of the fuel tank, directly under the carpet (and metal) where my 4 disc CD changer had been. I knew I'd have to lower the tank at least, if not remove it completely out of the car to get to the valve. I had tried getting at it from the wheel-well (impossible), and despite even lowering the tank so it sat on the front diff, I could just barely get my finger on it from the access panel under the battery. Before going further, I needed to absolutely be sure the valve was broken, so I disconnected the wires leading to it via the connector which sits under the battery tray, next to the tank pressure sensor. Applying 12V to the pins, I couldn't hear or feel anything from the valve. Dead. At this point I was sure the valve was broken. Interestingly, the coil resistance was the same as the replacement, so that's not a good indicator of functionality.

So, we made the call to drill a 4" hole directly above where the valve sits, through the metal panel under where the CD changer had sit (see picture). Not an easy call to make, but since the only other way was to drop the whole front diff and tank, i knew I'd be looking at some serious labor bill if I took it to a shop. A quick job with the holesaw, and we were able to easily replace the valve. Upon testing the system by manually pushing the metal flap in the fuel filler neck up, I felt the valve actuating! I'll be getting a bung to plug the hole in the future, but once the carpet is back on, you can't tell anything was done.

Took it the to the gas station, and was rewarded with the most boring fill up ever Hopefully this helps someone with hard to fix fuel fill issues!
Would be helpful to others. Nice work.
 
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Old 09-17-2018, 07:55 PM
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Originally Posted by Slider View Post
Yikes! That all I can say - I hope I don't get that one.
+1 lol.
 
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Old 09-17-2018, 11:59 PM
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Picture of hole location
 
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Old 09-18-2018, 08:47 AM
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Originally Posted by gadangit View Post
I have this same exact problem. The filling issue is intermittent. Some weeks I get a normal fill, others I get the 15 minutes at the pump. I now have an error code indicating a pressure problem, so the time is nigh to fix. Thanks for posting, I'll be doing this soon. Hopefully without the hole saw.
Check your filler cap! If there isn't a perfect seal while you drive, you will have a pressure problem that can cause the filler not to allow fueling. Also, twist the cap on until it clicks (at least once). It seems simple enough, but this can cause extreme headaches.
 
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Old 09-18-2018, 08:51 AM
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Originally Posted by Slider View Post
Check your filler cap! If there isn't a perfect seal while you drive, you will have a pressure problem that can cause the filler not to allow fueling. Also, twist the cap on until it clicks (at least once). It seems simple enough, but this can cause extreme headaches.
Interesting. My cap failed the TX emissions test a few years ago and I ran down to O'Reillys to get something that would pass. I'm not sure what is on the car, now that I think of it. How awesome would it be if I only have to get a OEM cap and avoid the hole saw treatment!
 
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Old 09-18-2018, 08:52 AM
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Originally Posted by benschwe View Post
Picture of hole location



 
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Old 09-18-2018, 08:54 AM
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Hey gadangit, as Slider said definitely check your fill cap, and also check fuse E6 (and any other electronics that may be tied to the circuit, such as a radar detector).
 
  #12  
Old 09-18-2018, 09:18 AM
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Originally Posted by benschwe View Post
Hey gadangit, as Slider said definitely check your fill cap, and also check fuse E6 (and any other electronics that may be tied to the circuit, such as a radar detector).
Definitely going to take a closer look tonight. What is interesting is the failure is intermittent and I know it will be a problem when I open the gas cap. I get the sound of a lot of pressure being relieved, I'm just not sure which way.
 
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Old 09-18-2018, 10:20 AM
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Originally Posted by gadangit View Post
Interesting. My cap failed the TX emissions test a few years ago and I ran down to O'Reillys to get something that would pass. I'm not sure what is on the car, now that I think of it. How awesome would it be if I only have to get a OEM cap and avoid the hole saw treatment!
Yeah - it clicks to let you know it is on tight enough and the mechanism won't allow you to over-tighten. How happy would you be if you did the hole treatment and still had the issue .
 
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Old 09-18-2018, 02:11 PM
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​benschwe,
Do me a favor and go out to your car and push the metal tab of the gas filler door all the way in and see if you hear a click.
 

Last edited by BauerR; 09-18-2018 at 02:15 PM.
  #15  
Old 09-18-2018, 03:50 PM
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OK, you lost me... No metal tab anywhere...
 

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