momentum / inertia problems

Hello, I’m making a 2d platform game and my player’s momentum is having problems. When I jump on a moving platform going up/right/left my character shoots in the direction the platform was going in much farther than a regular jump and he does not start falling down for a long time. How do I fix this? Any help would be very appreciated.

Thanks,
zAk

We would need to see code to help fix it, i cant really tell something from your explanation.