First boat - 60hp Bigfoot - trim won't stay up during above no wake operation - what is normal?

[beachatlast]

I have a 60hp Bigfoot on a 18' 96 crest pontoon. It trims and stays trimmed at no wake speeds, but not on high speed (goes all the way down). I read that this might be normal? How do you adjust plane if that is the case? How can I test to see if my trim is working as expected? It sure feels like I should be able to adjust the trim at least some when I am trying to get somewhere above no wake speeds (gulf bay in relatively shallow waters). I am actually hoping I have a trim leak / air bleed to resolve, trim release screw/o'ring. I do not have any guages on the boat to check rpm, etc... Maybe I need to get one to test trim stays up at certain RPM's? The back of boat stays low and gets water on deck at higher speeds and I am looking at getting a hydrofoil, but if I cannot adjust trim with the hydrofoil, would it make things even worse? I have a list of tasks to troubleshoot if it is not working as expected, but thought I would check to be sure I have a trim proble or not 1st. Thanks in advance for any advice.

 

[airshot]

You sure ut has power trim and not just tilt ? Many outboards just had power tilt only and would not hold under pressure of speed. Otherwise...you have a problem ....

 

[beachatlast]

You sure ut has power trim and not just tilt ? Many outboards just had power tilt only and would not hold under pressure of speed. Otherwise...you have a problem ....

Under the mercury parts catalog for my sn, it shows a bunch of trim parts (power trim kit, trim tab, trim switch kit, etc...). I only have one button for up and down.

 

[QBhoy]

Kind of depends how high the engine is. If you mean way up beyond the normal trim range and into trailer range…some engines won’t allow beyond a certain rpm.
But with this era of engine and the description or mention of the engine lowering itself under load, I’d have a confident notion that it’s almost certainly a hydraulic issue you have. Valves passing internally or rams externally perhaps. Better news might be if it was just needing oil.

 

[dingbat]

Sounds like you have air in the system. Needs bleed