Mercury 225 EFI, Service Manual

Page: 433 / 719

POWER TRIM - DESIGN II
90-884294 OCTOBER 2001 Page 5B-7
Power Trim - General Information
Description
The Power Trim System consists of an electric motor, pressurized fluid reservoir, pump,
tilt cylinder, and two trim rams.
The remote control (or trim panel) has switches that trim the outboard “Up” or “Down” and
tilt the engine for “Trailering”. The outboard can be trimmed and tilted under power or
when the outboard is not running.
Trimming Characteristics
NOTE: Because hull designs react differently in varying water conditions, varying the trim
position will often improve the ride and boat handling. When trimming from a mid-trim po-
sition (with outboard trim tab in a straight fore and aft position), expect the following:
TRIMMING OUTBOARD “UP” (OUT):
WARNING
Excessive trim “Out” may reduce the stability of some high speed hulls. To cor-
rect instability, reduce the power gradually and trim the outboard “In” slightly be-
fore resuming high speed operation. A rapid reduction in power will result in a
sudden change of steering torque and may cause additional boat instability.
Will lift boat bow, increasing top speed.
Transfers steering torque harder to port (left) on installations below 23 in. (584.2 mm) tran-
som height.
Increases gearcase clearance over submerged objects.
Excess trim can cause “porpoising” and/or ventilation.
WARNING
Excessive outboard trim angle will result in insufficient water supply causing wa-
ter pump and/or powerhead overheating damage. Insure water level is above wa-
ter intake holes whenever outboard is running.
The “Up” circuit actuates the up relay (under outboard cowl) and closes the motor circuit.
The electric motor drives the pump, forcing fluid thru passageways into the up side of the
trim cylinders.
The trim cylinders position the outboard at the desired trim angle in the 20 degree maxi-
mum trim range. The system will not allow the outboard to be trimmed above the 20 de-
gree trim range as long as the engine RPM is above approximately 2000 RPM.
The outboard can be trimmed above the 20 degree maximum trim angle (for shallow wa-
ter operation, etc.), by keeping the engine RPM below 2000. If the RPM increases over
2000, propeller thrust (if propeller is deep enough) will cause the trim system to return the
outboard to the 20 degree maximum trim position.