So, did the fuel tank capacity mod just now. Took about 30 min and a small cut in my wrist. Pulling that vent tube out was not too hard and am now looking forward to seeing how many extra miles I get to a tank. Anyone else done that mod? Any pros/cons?
Stoopid Jeep
YJ Enthusiast
No cons. Free increased fuel capacity.
The fuel gage will read full for a long time before it starts to drop. Since doing the mod, I usually fill my tank as soon as I see it's below the full mark.
Stoopid Jeep
YJ Enthusiast
Flyer58
YJ Enthusiast
I did it and didn't cut the tube as short as some others have, maybe an inch or two longer. The only problem I now have is I need to fill the tank slowly because it will overflow onto the ground before the pump handle kicks off. If I pump gas slowly it's ok.
Flyer58
YJ Enthusiast
Maybe it was just the high speed pump I was using. I still get a chuckle pulling the silenced plate down to get to the gas cap even though it's a PIA.
Pull the fuel tank vent tube, cut it shorter (or don’t reinsert at all) and button it back up. The gas pumps work to where when the gas reaches the vent tube, the tank vapor locks in a sense and shuts off the gas pump.
From 91-95 Jeep used a 20 gallon tank on all models, and limited most of them to 15 gallons by sticking in a long vent tube.
87-90 either have a 14.5 gallon metal tank or a 20 gallon non-limited plastic tank, so you can’t actually do the fuel mod. But you could swap to the larger tank if you have the smaller one. Kind of expensive to do that though.
There ar lots of YouTube videos on it. Took me about 30 min to do and was easy once you get ahold of the vent tube to pull it out.
Flyer58
YJ Enthusiast
With the poly tank you go from 15 gallons to 20 gallons BUT the fuel sending unit only shows the last 15 gallons.
Still good news because E = empty
Sorry, maybe I didn't ask that question clearly. If I have a 15 gallon tank and I do this mod on my current tank, how much additional capacity am I going to get over the original 15gal?
If you have an 87-90 you can’t do this mod. 87-90 Jeep had two separate size tanks. Metal 14.5 gal and poly 20 gal. In 1991 they consolidated the tanks down to one 20 gal tank and limited most of them to 15 gal by sticking the long vent tube down in there. If at the dealer someone opted for the “20 gallon tank” add on, the dealer would pull the tube and cut if. If Jeep was building a 91-95 Jeep to have a factory “20 gallon tank”, they inserted an already short tube into the vent slot.
If you have an 87-90 with 15 gallon limitation, then you have the 14.5 gallon metal tank. If you have a poly tank, then you have the 20 gallon tank and should be able to get close to that much gas into it if you drive it low enough.
For anyone with a 91-95 that does this mod, they will go from 15.3 gallons to 20.
Ah, I thought it was an option to add a little capacity regardless of which tank you had. Now I get it. I'll have to go check my current tank. I can't remember anymore, but I think Collins Brothers swapped out my tank a number of years ago because my original was cracking. I would've hoped they put in a 20gal, but the tank currently only holds close to 15. Maybe I've got the poly tank and can do this mod. We'll see...