2006 50 hp power trim trouble

[zx475ti]

i have a 2006 2 stroke 50 hp merc and i am having a problem with my power trim when the boat is moving forward. if i try to trim the motor up while moving the motor just jumps and then returns to a lower position. if i trim the motor up while sitting still and then shift to forward and apply throttle the motor returns to almost no up trim at all. while on the trailer the motor will trim all the way up and down with no hesitation or jerky movement at all. but i can trim the motor all the way up and push down on the skeg and the motor will move down like you were trying to trim down. i have checked all the fluid levels and they are fine also dont see any leaking fluid from anywhere on the trim system. trim motor sounds normal in al positions but when throttle is pushed in the water trim will not hold the motor position. any ideas on how to narrow down and solve my problem would be greatly appreciated.

thanks

 

[RRitt]

Re: 2006 50 hp power trim trouble

common problem on 50Hp after mid 1990's. It is the trim limit bypass. Chances are good that it will come back after repairs. It is a design mistake that needs to be corrected rather than re-installed. You need to raise the bypass pressure.

 

[zx475ti]

Re: 2006 50 hp power trim trouble

common problem on 50Hp after mid 1990's. It is the trim limit bypass. Chances are good that it will come back after repairs. It is a design mistake that needs to be corrected rather than re-installed. You need to raise the bypass pressure.

thank you for the reply i believe you are exactly right. a friend loaned me a service manual and as i was reading through i found the section on the trim limit feature which i believe causing the symptoms i have but there is no way to fix it short of replacing the entire trim system with an aftermarket one without the trim limit system. i did see you can change the spring on the valve in the bottom of the manifold but that would probably give you a few more rpm before the trim limit kicks in but wouldnt help at wot. if there are any other ways around the trim limit i sure cant find them.