Need turbo help

[RWH]

I have an apex mountain with a bender turbo. I am running at 12lbs of boost. When climbing it starts to sputter or pop back when held wide open. It doesn't do it on the trail. Any suggestions as to what to look for or what it could be.

 

[Ted Jannetty]

Get a fuel pressure gauge on it to see if it is running out of fuel or loosing fuel pressure.