Yamaha trim question

[JCAUTO1]

I have a 1997 Yamaha 150 with a trim issue. I can trim the motor up on standard or trailer trim and it will stay up for as long as needed but when I put the engine in reverse and throttle up, it kicks up., I've bled the system and it is full of fluid. also. there is no apparent leaks anywhere. Any help would be greatly appreciated.

 

[alldodge]

I have a 1997 Yamaha 150 with a trim issue. I can trim the motor up on standard or trailer trim and it will stay up for as long as needed but when I put the engine in reverse and throttle up, it kicks up., I've bled the system and it is full of fluid. also. there is no apparent leaks anywhere. Any help would be greatly appreciated.

Not a Yam expert but most all outboards have a lock down hook which holds the engine down in reverse. The hook (lever) is either solenoid actuated or mechanically done when the engine is put in reverse. Look along the motor for a hook type lever that when moved will hook over a rod or pin

 

[schematic]

Likely a valve in the TNT stuck open or a bad o-ring on the manual valve. I don't think the 150 has a mechanical lock linkage....

 

[JCAUTO1]

That's kinda what I'm thinking. I don't see any manual solenoid on this one. I've got twin 150's and the port motor doesn't do it. I looked at a schematic of the trim assembly and I cant really make sense of it. It would be nice to get a hydraulic flow chart. Someone else told me there is a valve that lets the fluid bypass in the event of an impact to the lower unit to allow the engine to kick up. I haven't seen this valve in the breakdown in parts. Does anyone know if it's part of the main piston assembly?

 

[JCAUTO1]

SOLVED!!!!!!-----I got hold to a guy that was really confident in the bypass screw seals being faulty. I ordered seals and pulled it apart. Broken inner o-ring on bypass screw. New seals and I'm back in business!!! thanks Johan de Kock <johandekock@gmail.com> for the help and thanks for the replies back on this issue.

 

[alldodge]

Thanks for letting us know the problem, happy boating