Gas cap venting

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Oct 28, 2018 | 07:37 PM

doc308

Thread Starter

Cruiser

Joined: Mar 2008

Posts: 187

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Gas cap venting

I have a '77 FXE equipped with the smaller, one-piece gas tank. Should the cap on this tank be vented? I notice quite a vacuum whoosh whenever I remove the cap after running.

Oct 28, 2018 | 07:57 PM

Racepres

Seasoned HDF Member

Joined: Jul 2014

Posts: 8,604

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From: Cental, MI

Certainly needs to be vented.
Actually it wouldn't run long, if Not vented... I suspect that when you remove the cap [especially on a Warm sunny day] the "sound" you are hearing is actually a Pressure release..
Prepare to get gas in yer mouth to test it tho... Many replacement automotive caps allow air in ... suck on the inside of the cap and air should come in, Blow on the inside of the cap, and no air goes out..
That is my suspicion anyway...

Last edited by Racepres; Oct 28, 2018 at 08:01 PM.

Oct 28, 2018 | 08:58 PM

johnjzjz

Seasoned HDF Member

Joined: Nov 2006

Posts: 12,878

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From: la la land jerzey

its actually better to get a new cap then suck on stale gas - just saying

Oct 28, 2018 | 11:08 PM

Squidbilly*

Road Captain

Joined: Jan 2016

Posts: 707

Likes: 165

From: Ashtabula Ohio

Common physics tell ya what must be replaced when extracting another material,
Thus no replacement creates a vacuum,

So yes drill a hole in the gas cap,