Plane out and trim drops quickly when moving. when still, trim drops within 45minutes from highest to lowest. Evinrude dealer has had boat for 4 days and says they dont have an answer.

LOW FLUID POSSIBLY AND THE PUMP DOES NOT PUMP WATER .

I have a 24 ft wi a 90hp. Cavatation usually results from improper trim. When reaching plane, watch bow. If bouncing, adjust trim so bouncing stops, then you are in proper trim for weight. Just like an airplane. Trim changes with number of passengers, moving passengers, etc.
Best of luck, captain.

Hello mark,
Remove Engine from Boat.
Loosen Swivel Tube At Top Of Mounting Bracket.
Remove all Ssecuring Bolts On Power Trim Body.
Disconnect Electric Cable.
Move transom Brackets Appart.
Remove Trim Unit.
Hope This Helps
Gordy

go google and type in --wiring schematics for johnson outboard motor 75 hp 1981 model --- and see if there is a pdf version for down load
repeat the search but change the name to evinrude and look for a pdf version down load
go to a dealer service center and see if you can get a schematics for each from them
while it can be expected that the wiring should be the same as each brand is made in a different factory there could be a slight difference in the wiring set up that is causing the problem

Russ, not sure on factory compression, forums say motor should be good if running 100+, more important is to be with in 10% from highest reading to lowest compression reading. Balance is a key part for engine to run good. Check the attached links,instruction and guides, Good luck
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http://www.iboats.com/basics/find_engine_compression.html
Two problems with 1977 Evinrude 115HP Two Stroke Need some help The Hull...
One Cylinder down on Compression

need a printout from the website, or check with the dealer..its a hydraulic pump setup used to raise/lower the outboard..to plane the boat out..