Layers not sticking together.

[flyntm 2]

I'm printing with PLA using a 0.4 nozzle in the Fast mode and the layers are not sticking together.  It sticks to the build plate and the part, which is about 400 mm high, does print. To my dismay, when I take the part off the build plate it just crumbles in my hands spliting across the layers at several levels It also appears that the vertical walls did not bond to each other or to the infill.  I'm thinking this is only happening in the Fast mode.

 

Any suggestions as too where I should start looking would be appreciated.

 

Thanks