I was testing two MS201TC fuel tanks by installing the flippy cap, plugging the fuel line opening, and checking vacuum (and pressure) through the tank vent grommet. Could not get the slightest P or V on either. Reinstalled same flippy caps with same result. Tanks and caps had been cleaned. Out of curiosity, I removed the o-rings, turned them over and reinstalled them. Both tanks and caps now held P and V perfectly. I'm not bashing flippy caps, but wondering if anyone has tried this as a quick fix in the field for fuel caps. Obviously, I'm not sure how long this would last or whether it would work every time. Also, has anyone tried aftermarket o-rings made of different, more chemical resistant rubber? I found Buna and FKM rubber rings for about 50 to 70 cents each on ebay.
