Troubleshooting
Determining if Problem is Electrical
or Hydraulic
When a problem is encountered with the Power Trim
system, the first step is to determine whether the malfunction is in the electrical system or the hydraulic
system. Refer to the following chart to determine
which system is at fault.
Problem Chart
Outboard will not trim up or down.
Outboard trims up, will not trim
down.
Determine if Power Trim pump motor operates when appropriate trim
circuit is activated.
Outboard trims down, will not trim
up.
Outboard will not return completely
to down position or returns part
way with jerky motion.
Pump motor operates.
Pump motor does not operate.
Refer to Hydraulic System
Troubleshooting.
Refer to Electrical System
Troubleshooting.
Outboard thumps when shifted.
Outboard trails out when backing off
throttle at high speed.
Outboard will not hold a trimmed position or will not remain tilted for any
extended period
Outboard will not hold trim position
when in reverse.
5B-6 - MID-SECTION
90-830234R3 DECEMBER 1997
Hydraulic System Troubleshooting
Date Code Location
Support outboard with tilt lock lever when servicing
power trim system.
Date codes are placed on power trim assemblies at
date of manufacture. These date codes are designed
to quickly identify assemblies which may be affected
by service bulletins pertaining to specific problems.
Note date code on trim assembly and compare to
date code listed on service bulletins before making
repairs.
After debris or failed components have been found
(during troubleshooting procedures) disassemble
unit completely and replace all O-rings. Check ball
valve components and castings must be cleaned using engine cleaner and compressed air or replaced
prior to reassembly.
Power trim system is pressurized. Outboard must be
in the full UP position (cylinder fully extended) prior
to fill screw or manual release valve removal.
Refer to instructions following if disassembly is required.
Follow preliminary checks before proceeding to troubleshooting flow diagrams (following).
a
53948
a - Embossed into the CAUTION Decal on Trim/Tilt Cylinder
90-830234R3
DECEMBER 1997
MID-SECTION - 5B-7
Preliminary Checks
Operate Power Trim System after each check to see
if problem is corrected. If not, proceed with the next
check.
2. The spool is considered stuck when the pin end
is protruding out past the end of the sleeve.
1. Check that manual release valve is tightened to
full right (clockwise) position.
2. Check trim pump fluid level with outboard in full
UP position and fill if necessary. Refer to Fill
and Purge the Power Trim System.
3. Check for external leaks in Power Trim system.
Replace defective part(s) if leak is found.
SPOOL STUCK
52790
a - Spool Pin
4. Outboard not holding tilted position (falls to trim
in position) indicates debris or defective components in trim valve assembly. Clean or replace
components as required.
5. Check manual release valve for broken stem and
one O-ring remaining in the release valve passage. (Separate the manifold assembly from the
cylinder to dislodge broken stem.) Install new release valve and test system.
52791
SPOOL NOT STUCK
6. Check for nicked, deteriorated, or misplaced
O-rings throughout trim system.
Leak Down Check - Pump and
Manifold Assembly
The 1993 and 1994 models listed with power trim
date codes 13011 through 23288 ONLY may experience a very slow trim rate (one minute or more) with
the outboard drifting back down as soon as the UP
trim button is released. This failure usually occurs
when the unit is new or after 3 or 4 weeks of non use.
The cause may be a stuck spool inside the sleeve
due to an oversize or a hard O-ring on the spool
(SERVICE BULLETIN No. 93-22A).
a
1. Remove tilt cylinder from the manifold and replace pilot valve assembly.
Pilot Valve and Seat Removal
a
b
c
d
e
Pilot Valve
Valve Seat
Return Spring
Sleeve
Spool
a
50999
a - Sleeve with Spool Inside
5B-8 - MID-SECTION
90-830234R3 DECEMBER 1997
3. A leak path is created between the UP side of the
cylinder and the reservoir when the spool sticks
holding the pilot valve open.
6. Inspect for nicked, deteriorated, or misplaced
O-ring.
d
a
a
b
c
d
e
f
b c
Cylinder/Manifold Mating Surface
O-ring
Spool
Return Spring
Valve Seat
Pilot Valve Held Open (away from valve seat)
4. Power trim units with date code 23289 and higher
have improved O-rings and improved surface finish on the inside of the sleeve to correct the problem.
5. To correct a slow leak down, check for debris between the valve seat and valve.
c
a
b
c
d
51560
Valve and Seat
O-ring
O-ring
Scribe Mark
Reassembly
1. Install the spool into sleeve from the chamfered
end (end opposite the cross hole).
2. Insert spool into sleeve until end is flush with the
chamfered end of the sleeve. Inserting the spool
too far into the sleeve may allow the spool O-ring
to contact the sharp edges of the sleeve cross
hole and damage the O-ring.
52792
3. After reassembly, insert driveshaft and check
pump rotor resistance to turning - housing halves
can shift/turn during reassembly. Align scribe
marks carefully.
a - Chip under Valve Tip
b - Rubber Seat
90-830234R3
DECEMBER 1997
MID-SECTION - 5B-9
Power Trim Partial Leak Down at
Maximum Trim
Power Trim Date Code 14182 and Below Service
Bulletin No. 94-13.
3. Remove all burrs and filings from the memory
piston.
4. Reassemble the trim/tilt ram assembly using new
O-rings and seals.
Some units, when trimmed to the maximum 20 degree limit, will leak down approximately 5 degrees
and then hold. The leak will ONLY occur while the
boat is under power. The cause for the 5 degree leak
down is the lack of a fluid passage between the shock
piston and the memory piston.
1. Disassemble the tilt ram assembly and remove
the memory piston.
2. Cut a small groove 0.020 - 0.040 in. (0.5 - 1.0mm)
deep across the top face of the memory piston.
The groove will allow oil passage when the shock
piston and memory piston are in contact. The
groove can be made with a hacksaw or triangular
file.
a - Shock Piston
b - Memory Piston
c - 0.020 0.040 in. (0.5 1.0mm) Groove
5B-10 - MID-SECTION
90-830234R3 DECEMBER 1997
Leak Down Check - Pilot Valve
Assembly
Leaks Past Ball and Seat - Piston
Assembly
1. Debris or chips between valve and seat (a), usually imbedded in rubber valve seat.
Unit will trim to full or near full down position and then
will begin to trim up while trim switch is held in
DOWN mode.
2. Pilot valve installed from non-chamfered end of
spool, results in nicked or damaged O-ring (b).
3. Nicked or deteriorated O-ring (c).
A leak path is created between the UP side of the cylinder and the reservoir. The trim system will leak
down until the trim port in cylinder is covered.
If trim switch is released, outboard can be pushed (by
hand) down to the point where trim UP started.
1. Inspect balls and seats in piston assembly for debris or damage. Repair or replace balls/seats.
c
a
b
a
51560
51143
a - Valve and Seat
b - Pilot Valve O-ring
c - O-ring
a - Ball and Seat. Check all for debris or damage.
Leak Down Check - Manual Release
Valve
1. Debris or chips under O-ring (a).
2. Flash from valve molding causing O-ring (a) to
not seal.
3. Nicked O-ring (a).
51560
a - O-ring
90-830234R3
DECEMBER 1997
MID-SECTION - 5B-11
Power Trim Rocker Arm
Power Trim Date Code 14182 and Below. Refer to
Service Bulletin No. 92-12.
Outboard in the trim position will not trim up or down
OR pump motor will lock up (not turn) in either direction.
2. Clearance between the side of the rocker arm
and each pin is 0.001 to 0.010 in. (0.025
0.25mm).
3. Torque bolt to 125 140 lb. in. (14.1 15.8 Nm).
a
d
Outboard in the tilt position will not tilt up or down OR
pump motor will run slow in either direction.
Single ram power trim that will not trim or tilt up or
down may have a pump/manifold assembly with a
broken rocker arm.
1. Replace broken rocker with improved rocker arm
assembly 823180.
a
a
51560
a - Clearance Between Each Pin and Rocker Arm
0.001 to 0.010 in. (0.025 0.25mm)
b - Pump Pins
c - Rocker Arm
d - Bolt [Torque to 125 140 lb. in. (14.1 15.8 Nm)]
a - Rocker Arm
b - Rocker Arm Assembly
Previous Rocker Arm Design
Improved Rocker Design
5B-12 - MID-SECTION
51742
51742
90-830234R3 DECEMBER 1997
Troubleshooting Flow Diagram
Outboard falls to full down position
with manual release valve closed.
Example a: Outboard lowers more
than one tilt bolt hole in eight hours.
Example b: Outboard lowers during
acceleration.
Inspect Manual Release Valve.
Result
Result
Manual release valve and/or Oring damage.
Manual release valve and O-rings
appear to be OK. Replace O-rings.
Replace defective valve and O-rings.
Result
O-rings appear to be OK. Cylinder
bore and memory piston are OK. Replace O-rings and proceed.
Inspect O-rings on Pilot Relief Valve
(located in manifold assembly).
Result
Result
O-ring failure.
O-rings appear to be OK.
Replace O-rings.
Replace O-rings.
Inspect Memory Piston O-ring.
Result
All components appear to be OK.
Replace Manifold and
Pump Assembly.
90-830234R3
DECEMBER 1997
Result
O-ring or Cylinder
Bore Defective.
Replace O-ring or Components.
MID-SECTION - 5B-13
Troubleshooting Flow Diagram
Outboard will not hold tilted position in
reverse and/or trails out during high
speed deceleration.
Inspect Manual Release Valve.
Result
Result
Manual release valve and O-rings appear to be OK. Replace O-rings and proceed.
Manual release valve and/or
O-ring damage.
Replace defective valve and O-rings.
Inspect Trim Rod Piston Check Valve.
Result
Result
No debris or defective
components found.
Debris found in check
valve components.
Inspect Manifold
Thrust Valve.
Reverse
Clean check valve components
using engine cleaner and compressed air or replace.
Replace Pump and Manifold Assembly.
5B-14 - MID-SECTION
90-830234R3 DECEMBER 1997
