New Fuel Cap Is Junk!

KCTractors

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Location
Central Wi
Just got a new gas cap for a 641, the gas-tank opening is in excellent shape, but the new cap is real loose on it, probably just laying on the opening. When I run the tractor, the cap will not vent and the engine will stop. I know that it is the cap doing it because I took out the drain-plug from the bottom of the carburetor and no gas in carb. I opened the gas cap and the gas started coming out of the drain plug. Anybody else have this problem with these new caps?
 
(quoted from post at 22:43:02 11/17/14) Just got a new gas cap for a 641, the gas-tank opening is in excellent shape, but the new cap is real loose on it, probably just laying on the opening. When I run the tractor, the cap will not vent and the engine will stop. I know that it is the cap doing it because I took out the drain-plug from the bottom of the carburetor and no gas in carb. I opened the gas cap and the gas started coming out of the drain plug. Anybody else have this problem with these new caps?
don't know, but "loose & laying in the opening" sounds completely inconsistent with" holding a vacuum & preventing flow".??
 
Got it from a Dealer that sells used and after market parts. I do know that it is causing a vacuum when running. Take the cap off and it will run.
 
I had the same problem with a cap bought from the dealer. "It's vented" I was told. Nope.

I just slapped my old cap back on there. Runs fine now.
 
Hi
Either that makes 3 of us that's not to bright , or we are missing something here.
I wonder if the inside part of the cap that locks in to the filler is tight on the tank, and its just the tops loose Like the chrome bit on some twist lock caps, if that makes sense.
some caps Ive seen are 2 piece and riveted or joined some how. That's the only way i could see it sealing a vacuum, and then undoing it makes fuel flow,and its not vented through to the outside between the inner and outer cap. I can't see fuel flowing sucking that cap down tight on a running tractor if it's that loose. Could be wrong though, wouldn't be the first time.
Regards Robert
 
i guess at this point we'd need to see his cap to see how it can both be loose and yet hold a vacume. wopuld have to be a semi 2 part cap with outter portion able to rattle on inner portion that is clamped down almost.
 
Totally agree on seeing it. it's kinda like the cup I got here now, in front of me. whats in it tea, coffee, paper clips or empty! You guys don't know cause you can't see it L.O.L
Regards Robert
 
Well my experience with new caps is the gasket. 6 months and it's dried out and cracked. So, after 6 mos. you don't need it to be venting and yes if this cap was vented it had to be between the shiny chrome cover and the latching part.

Mark
 

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