1990 88 hp johnson will not hold trim under acceleration

[SSPrint]

Hello, The tilt trim works like new in the driveway. In the water, if you have the trim up and give it gas, the trim bottoms out very quickly. While accelerating, you can not get the motor to trim up.
Thanks for any ideas
Mike

 

[interalian]

Checked the oil level? Tilt all the way up and pull the slotted screw. Add Dexron ATF until full, cycle up/down and re-check.

Make sure the manual release valve is tight - slotted screw in hole low on stbd transom bracket.

 

[nanuk]

I bought a '77 with what was supposed to be TnT, but turns out it is ONLY Power Tilt

are you sure you have one with BOTH Tilt and Trim?
New to you?
Has it worked correctly under power before for you?

got a picture of your unit?

 

[SSPrint]

Hello Nanuk, Tried to add photo said the file was too big. I have had the boat since new. Alwasy had tilt&Trim and worked great 25 years.
Thanks
Mike