too much yeast

[cross eyed]

is it possible to ferment your beers with too much yeast

[Diamond Knot]

Yes. Definitely, in my opinion.
Flavor arguements aside, too much yeast will produce too violent a ferment with excessive daughter cell producion. You lose beer volume to all the excessive yeast produced.

[Moonlight]

If your question was: can one pitch too much yeast...definately. You will likely end up with a sluggish fermentation and all lame geriatric cases when you go to repitch. Flavor may suffer as well.
As a rule, there should be a 3 to 4 fold increase in yeast from pitching volume to harvest volume for optimal health. If you harvest too much, back off of your pitch rate, and vice versa. Something will suffer if you are out of this range.

[SRB]

woe is me.
Lesson learned.

thx for the info.

[beerking1]

Flavor WILL suffer. Oddly enough, the off flavors are very much the same as underpitching can lead to (acetalldehyde, diacetyl, fusels...).