Background: I'm replacing my leaky 19 gallon TJ tank with a new/used one I got. Unfortunately, the new one is a 15 gallon tank. The tank itself is identical. All that's different are the vent and filler tubes that are "welded" to the tank. The 15 gallon tank uses tubes that extend further into the tank (by about 3-4")... to trick the gas pumps out of seeing those last 4 gallons.

I've seen a writeup out there that says you can simply cut the long tubes down to the length of the 19 gallon tubes ... simple enough.

What has me concerned though is that in doing that, you also end up cutting out what appears to be a roll over valve of sort on the filler tube. It has a hollow plastic ball inside a cage. It doesn't seem to make a perfect seal when it floats up, so I am wondering if this "thing" has more to do with the gas pump dealio than anything.

Can someone explain to me what this ball is for?

I can't see it being a roll over valve because the fuel could still sneak around it by going through the unchecked vent tube. I'm presuming that the TJ filler neck has a spring loaded check valve in it anyways plus the sealed cap.

I fear simply omitting this ball if I'm gonna' start overfilling my tank at the station. Can I leave it or do I have to remove it to get access to those last 4 gallons?

Thanx.

cmk

I have no knowledge of jeep stuff, so DON'T quote me. I think that the platic chingadera you are describing is the anti-siphon valve. If it is, ditch it. I don't think you will have to worry about any adverse effects, other than makin it easier for thieves to take your fuel.... Don't worry about over filling the tank. The pump is designed to shut off the second any backpressure is felt (or at least that is how they always work for me) As long as the vent tube works, the gas will stay inside the tank (under normal circumsances)

Good luck

Here's a pic of the dealio I am referring to. It's the tube on the far left hand side of the pic.

http://pages.prodigy.net/coolmank/pics/jeep/gastank/insideTJtank.jpg

cmk