Huskee Lt4200 motor dies while going down hill

[robhumph]

I have a 2013 Huskee Lt 4200 42in riding mower that runs fine until going down hill then engine dies, if I disengage the blades it runs fine or get it back on level. ground I can engage the blades again runs fine. Any suggestions would be great

 

[bertsmobile1]

Water in the fuel tank