Re: Yamaha I/O power trim motor
You have two check valves that screw out the sides of the pump. One in the left side and one in the right side. One of these is leaking and allowing the fluid to bypass. I can't remember which is up or which is down. Also you could be having a problem with the manual bypass on the front, flip the lever several times and see if it works OK after that. As for the check valves, I think I still have one or two laying around. They invented a special pressure tool for checking these valves and they did have a problem with them early on. Thank goodness I didn't buy the tool or it would be gathering dust like the rest of the special tools we had to buy.
