If the pacific ocean has so much water, why do hurricanes in the eastern pacific die before they reach asia?

Water temperature plays a big role. If the water is cooler as they move across the ocean the hurricane will lose strength.

True, a lot is water temp. If the ocean drops more than a degree or so under 84 F there won't be enough latent heat to power the hurricane. It also has to do with wind shear high up in the atomosphere. If there's too much shear the storms in the hurricane will get torn to shreds and it will dissipate. If you've heard of El Nino and La Nina then you should know that has an effect as well. Mostly just because it changes wind shear levels and water temps from one ocean to another. During La Nina years Pacific hurricanes tend to intensify and occur more often.

Coriolis force deflects the winds to the right in the northern hemisphere.So any pressure system which is moving from east to west in the northern hemisphere over large oceans is deflected towards the polar side and thereby they are forced to enter cold waters.Cold waters usually weaken a hurricane.In the case of hurricanes which form in the eastern Pacific,they travel a vast ocean,get deflected towards pole side and enter cold waters(without encountering any land area in which case they may cause severe damage) and subsequently get weakened.So,they form and get weakened without causing any damage.So they go unnoticed.