Fuel Cap For Plastic Tank

So I filled up my gas tank today and shortly after made a right turn. This made me realize my gas cap leaks. I have an under seat plastic tank. Should this cap have the rubber gasket? Is it the same cap as a metal under seat tank?


Thanks,
Ken

 

Your cap appears to be a reproduction of the original AC/Eaton cap, and yes, there is supposed to be a flat rubber gasket to seal it to the tank.
-Donny

 

Thanks for the reply. Any tips on a part number for a replacement? Searching around a see a lot of caps listed as "non-vented", is that appropriate for my application?

 

Unless you have a return line, you will need a vented cap.
-Donny

 

I have a plastic tank in one of my Jeeps and the cap I used is the same one that was on the steel tank that was in it. Mine is a Stant, it is vented, and yes it does have a gasket, but I don't know the model number.

With a full tank most of these Jeeps will burp a little gas, it is better not to fill it to full capacity.

 

This is a V6 application and it does have a return fuel line from the fuel pump. So I don't need a vent then? Thanks for the help

 

The return is not a vent. Instead it circulates fuel from the tank to the pump and back to keep the fuel cooler.

The vent is through the gas cap. You must have a vent so the fuel level can go down and more air can come in.

In my experience, these under seat tanks will leak a little on side-hill or when there is a lot of sloshing. It helps to leave some extra room above the fuel.

 

Thanks for the replies. I ordered a replacement cap from Gates, hopefully I can just swap the gasket.

 

If it is an MTS tank the best bet is to get a cap from MTS. None of the ones for the factory steel tanks I had fit properly whereas the MTS cap fits very well. The issue I had was the thickness of the plastic where the tabs engage the next and lock it in place. What was said above about not filling to the top.

 

I have a re-popped steel tank and it's the same way, if I fill the tank and park it on a sidehill it will leak too. I leave it a little low when I fill up.