Hi there, your engine serial number isn't coming up as a valid number anywhere. It seems it has one number to many someplace plus I can't find any number in the 80 HP that's has an 8 after the A. They all seem to start with a 9. Can you post a photo of the serial number and maybe the engine as well?
Also is it a 3 or 4 cylinder?
Merc part number 90-13645--2 covers service manuals,
70/75/75 Marathon/75XD/75 Sea Pro 80/90 (3 Cylinder) 1987 thru 1993 AND 100 & 115 (4 Cylinder) 1988 thru 1993
(U) 0A997142 thru 0D283221 (B) 09502135 thru 09793576 (C) 0A722297 and Above
(U) 0B209468 thru 0D283221 (B) 09523034 thru 09793576 (C) 0A731673 and Above
And merc part number 90-86134--4 covers service manuals,
75, 80 & 85 (4 Cylinder)
AND 90, 115 &140 (In-line 6 Cylinder)
AND 150 (In-line 6 Cylinder)
(U) 4590512 and Above (A) 8043775 and Above (B) 9139350 and Above (C) 7091098 and Above
(U) 4112635 and Above (A) 8027115 and Above (C) 7047258 and Above
(U) 4121435 and Above (A) 8028040 and Above (C) 7048783 and Above