Interesting Pics of the Inside of the Gas Fill Tube at the Tank

[JTenn]

A few weeks ago I installed a full belly skid system from Next Venture Motorsports. Ever since, I am having a very difficult time getting the gas tank all the way to full, meaning it will fill up and click off and I can virtually dribble 3 more gallons. I can eventually get it full but it takes a while. I've never had a gas burping issue but I know others have. So I bought a bore scope to make sure I didn't kink the fill tube during installation. These pictures are interesting to see what is down in the fill tube at the gas tank. I'm assuming this is a valve connected to a float in the tank that seals up the fill hole at the tank inlet but still allows gas to slowly seep in through the fingers allowing a slow controlled top off. There is an o-ring around the white plunger and under the blue fingers. Nothing kinked on my fill tube so next I'll check to make sure the tank is level. Just really wanted to share the pics. Sorry for the pixelation but I just took pics of the bore scope monitor.

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[Broccoli]

That’s just the cervix.

 

[JTenn]

That’s just the cervix.

Looks like it, lol. Or the Terminators butt hole.

 

[kubankevin]

I would recommend against topping off. You can ruin the evap / charcoal canister by doing so.

that being said, my two door JL had this issue from time to time where the tank would be empty and attempting to pump at full speed would make it click after just two or three gallons. I’d get around it by pumping manually at half speed. My job truck F-150 does this here and there as well.

 

[JTenn]

I would recommend against topping off. You can ruin the evap / charcoal canister by doing so.

that being said, my two door JL had this issue from time to time where the tank would be empty and attempting to pump at full speed would make it click after just two or three gallons. I’d get around it by pumping manually at half speed. My job truck F-150 does this here and there as well.

Yeah this is a new issue definitely caused by me disturbing the tank mounting. I didn't drop the tank for installation but I did ratchet strap it in place to remove the factory skid. But the tank inevitably shifted during all this. This plunger is closing too early during a fill up. The gas gauge will literally only go to 7/8 full now. I agree about not topping off and I don't on any of my vehicles. Never have but I can get 3 more gallons in the tank which is not normal.

 

[fourfa]

Oh, interesting. I just installed the same belly plates, same ratchet straps holding and moving the fuel tank around (diesel in my case), same thing where now I'm getting a couple less gallons in at fill-up than I'm used to. Gauge still reads full, but starts immediately dropping instead of staying at full for a little while. I didn't think to associate it with the plate install until you pointed this out.

 

[JTenn]

Oh, interesting. I just installed the same belly plates, same ratchet straps holding and moving the fuel tank around (diesel in my case), same thing where now I'm getting a couple less gallons in at fill-up than I'm used to. Gauge still reads full, but starts immediately dropping instead of staying at full for a little while. I didn't think to associate it with the plate install until you pointed this out.

I ran my tank to nearly empty before the installation as NVM suggested so I'm positive this started after installation. My first drive was to fill the tank and that's when I noticed it. I've had my truck since new and have 50,000 miles on it now. It has always filled up until now.

 

[Alan_Hepburn]

I believe that valve is the anti-siphon valve that's been installed in vehicles for several decades now - it's purpose is to prevent miscreants from siphoning out all your go-juice. It also prevents spillage in the event of your vehicle going belly-up.

 

[JTenn]

I believe that valve is the anti-siphon valve that's been installed in vehicles for several decades now - it's purpose is to prevent miscreants from siphoning out all your go-juice. It also prevents spillage in the event of your vehicle going belly-up.

I agree that it is the anti siphon valve. I also believe it is the culprit to the fuel burping issue many on here experience. What I'm not sure of is if it's spring loaded or has a float or a combination of both. I would think the weight of the incoming fuel over comes a spring but a float that rises with fuel level pushes it closed when full. I could be totally wrong though but it makes sense in my simple mind.

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