Troubleshooting - Mercury 150 EFI Service Manual

POWER TRIM

Troubleshooting

IMPORTANT: Determine if Electrical or Hydraulic problem exists.
IMPORTANT: Acceptable power trim leak down should not exceed 1 in. (25.4 mm)
(when measured at the tilt ram) in a 24 hour period.
HYDRAULIC SYSTEM TROUBLESHOOTING
IMPORTANT: Make one correction at a time. Check operation of trim system before
proceeding to the next check.
CONDITION OF TRIM SYSTEM
A. Trim motor runs; trim system does not move up or down.
B. Does not trim full down. Up trim OK.
C. Does not trim full up. Down trim OK.
D. Partial or "Jerky" down/up.
E. "Thump" noise when shifting.
F. Does not trim under load.
G. Does not hold trim position under load.
H. Trail out when backing off from high speed.
I. Leaks down and does not hold trim.
J. Trim motor working hard and trims slow up and down.
K. Trims up very slow.
L. Starts to trim up from full down position when "IN" trim button is depressed.
M. Trim position will not hold in reverse.
PROBLEM
1. Low oil level.
2. Pump assembly faulty.
3. Tilt ram piston ball not seated (displaced, dirt, nickel seat).
4. Tilt ram piston O-ring leaking or cut.
5. Manual release valve leaking (check condition of O-rings) (Valve not fully closed).
6. Lower check valve not seating in port side trim ram.
7. Upper check valve not seating in port side trim ram.
8. Check condition of battery.
9. Replace motor assembly.
10. Broken motor/pump drive shaft.
External Mounted Hydraulic
System
Page 5B-12
1
1
3
3
7
7
4
4
6
PROBLEM
1, 2, 5, 10
2, 3, 4
1, 6
1, 3
2, 3, 6, 7
5,8, 9,10
2, 5, 6
3, 4
2, 5, 7
8, 9
1, 2, 8, 9
3, 4
3, 4
2
2
10
5
5
51491
90-883728 JULY 2001