[havasu2009]

1990 25.5 sx ,I just bought this boat and drive was down,trim wont come up

[TilliamWe]

Are you using the "trailer" button or the "trim" button?

[havasu2009]

I hear the relay on the trim down, but nothing on trim up,no action when using trailer up

[TilliamWe]

Time to check power at the pump. Sounds like an electrical issue. Sounds like you may have a few of them?!

[havasu2009]

found loose down trim connection,it works need to replace up relay,also replaced water pump and t-stat temp stays at 180

[TilliamWe]

Good job. If you are using the boat in freshwater exclusively (I know Lake Havasu is fresh water), then 180 degree thermostat is fine.
In the olden days (70's and 80's) Mercruiser used to put 120 degree stats in! They did that, cause if run in saltwater, the lower engine temp would help keep the salt from crystallizing as bad inside the motor. If you ran in fresh only, you could put in a 140 degree. Later, Mercruiser changed to 140degrees standard, with 160 being the optional. However, as you know, in a GM truck, a 7.4 (454) would have a 195 degree stat. So 180 is just fine.