Bought a new gas cap for dad's 640. Description said it's vented. Got lots of pressure in the tank when using the cap. Got another on order. It's a little different in appearance.

Anyone ever experience a vented cap that didn't vent? Thought about getting the drill out. LOL!

Tyler (MD)

I will take a WAG here that the vent path is as shown in red, with loosely drawn line being under the center piece and under the gasket all the way to edge. There, just not easily seen.

Yes,

Both style caps that I own have the center hole in them. I just don't know why there is pressure in the tank when I unscrew the gas cap. I figure there shouldn't be any.

Tyler

Perhaps the vent hole is beneath the warning sticker?

Good idea. I'll remove the sticker and check it out. In the meantime, I purchased this style of vented cap. Shown is the one I had years ago on the tractor. Humm.....guess I'll find out if this one is really vented. :-)

Tyler

I have a 850 with a drill vented cap. Works quite well.

Do you drill all the way through from the top of the cap down?

Thanks Bruce!
Tyler

I did. About a 1/32 inch hole. Might not be smart, because:
Now if your bouncing around all the place how much fuel leaks out?
Vapor control?
It's not wet fuel that burns. It's the vapor that is more explosive.
I did the fast drill just to eliminate a problem.
I should go look for an actual vented cap.

Personally I got tired of running out of gas with a full tank! 1/8 inch drill bit through the center of the cap and ran fine. Never noticed any splash out.

Thanks guys. I'm drilling the cap. Going to use it as a spare and hope the other one I ordered actually vents.

Tyler

I bought a gas cap with a gauge from Red Rock a few years back. I couldn’t use the gasket because it wouldn’t tighten down with it. It was still tight because there was no venting and the 8N stalled out. I drilled a 1/16 inch hole through the clear top of the gauge and it works fine.