When I engage blades the mower just dies

[BmPoKeRsTaR]

One thing it won't be is the pulley
Before we can give you any meaning full advice we need to know what mower brand & model we are talking about

Exmark Quest qst22be482 48 inch cut

 

[Forest#2]

Are you setting in the seat when you pull/engauge the pto?

Did you remove the dec?

Was it working ok before you replaced the pulley?
If so you might just try reversing what you changed when installing the new pulley replacement pulley.
Some decks even have a discharge chute switch that must be re-connected.

Summary: check the electrical plugs to any safety switches you may have un-plugged or monkeyed with.

 

[StarTech]

Okay as long you have the parking brake in park and both lap bars out in neutral position. Then as you turn the PTO the kill relay voltage switches from being provided by the PTO switch to being provided by the seat switch and its wiring.

Wiring colors are different on your model then on the diagram I posted but the basic wiring is the same.