General Specifications
HP / kW
90 HP / 67.0 kW
Displacement
1500 cc (91.5 cu in.)
Cylinders
6 (Inline)
WOT RPM
5000 - 5500
Weight
125 kg / 276 lbs
Drive & Lower Unit
Gear Ratio
2.0
Shaft Length
20", 25"
Electrical System
Alternator Output 201 Watts
Starting System Electric
Technical Maintenance Toolkit
Verified service specifications for the Mercury 90hp (Inline-6 Tower of Power) (1978)
Lubrication
Engine Oil
TC-W3 2-Stroke
Gearcase Lube 665 ml
Ignition System
Spark Plug
NGK BUHW
Firing Order 1-2-3-4
Performance Specs
Idle RPM 700 ± 50
WOT Range 5000-5500
Alternator 201W
Standard Maintenance Intervals
20H Break-in Service
100H Annual Tune-up
300H Water Pump & Seals
Identification
The serial number for the Mercury 90hp (Inline-6 Tower of Power) is typically found on a plate located on the transom bracket.
Technical Toolkit
Maintenance Compatibility
These models share common service parts with the Mercury 90hp (Inline-6 Tower of Power):
Model Evolution
History of the Mercury 90HP series over the years:
Category Discovery
Reference Data
Information compiled from Mercury Marine factory service manuals and original sales literature published in 1978.