Hello,

I finally took out my gas tank today, and I had purchased a "genuine GM" gas cap for the car as well.

Well it doesn't seem like the gas cap seats all the way to the rubber seal. I have a vented cap as well that I bought cause whenever I'd fill up, fuel would inevitably spill out from the gas cap, I thought it was a venting issue. I got a new fuel tank vent, but haven't been able to fill it up since I installed it so I don't know if that took care of my issue or not.

When putting on the vented cap, it definitely seats closer to the rubber than the "Genuine" one, but I have no idea how these are supposed to sit/seal.

Any advice?

 

The replacement tanks have a different thread. No idea how that could possibly be A Good Idea but w/e. Been discussed on here quite a bit. Do a search on "gas cap thread" and stuff like that, and see what comes up.

Bottom line I'm afraid will be, your "genuine GM" cap is no longer applicable.

Avoid a vented one if possible.

 

It appears my tank is stock, it has a Made in Canada sticker on it, though I guess that's not really a sign of anything lol.

Either way, I ordered the Stant 10819 Pre Release fuel cap. Apparently this is the one I need. If not I will continue the hunt.

 

Just been through this and I used a dremel and small sanding drum to grind a little height off the thread on the old cap. didn't take much but allowed the cap to seat correctly on the new tank filler neck. The cap should screw in with little resistance until it seats and when it is the skirt of the cap should be just below the roll on top of the filler.

 

We will see how the stant cap works, if it doesn't pan out, I will look into modifying something!

 

I just got a 4th gen cap for my Dorman tanks and they work just fine. Previously I used my pocket knife to shave down the threads on my original cap and got that to work also - being eager to finish the job and all I had to make it work. Replaced it once I found out that all I had to do was get a 4th gen cap.

GD

 

Is the 4th gen cap a vented cap? If so how does it interact with the stock vent valve? Should the stock vent be blocked off if a vented cap is used and does a new vented cap function the same as the stock vent valve?

 

No - 4th gen is not vented. They went away from vented caps in the 70's when they introduced carbon canisters. From the early-mid 70's on there were no cars to my knowledge that used vented gas caps.

GD

 

I put a thread together a while back with the gas caps that people have had luck with. part#, ect, its all there.