1999 Mercury 30/40 FourStroke Outboard Motor Service Manual

Complete 1999 Mercury 30/40 FourStroke outboard motor service manual for troubleshooting, removal, and installation procedures. Includes diagrams and specifications.

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Document Details

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Document Number / Seller:
29834 / Peter Murphy
File Size:
19.73 MB
File Type:
PDF
Language:
English
Printable:
Yes
Category:
Outboard Motor
Last updated / verified
Oct 23, 2025

Models Covered & Key Technical Specifications

Mercury 30/40 FourStroke (90-857046R1 NOVEMBER 2001) - 1999 FourStroke 4-Stroke Over Head Camshaft | Outboard Motor Marine Engine Logic.

  • Engine Type: 4-Stroke Over Head Camshaft
  • Displacement: 45.6 cu. in. (747 cc)
  • Horsepower: Model 30: 30 hp (22.4 Kw) @ 5750 rpm Model 40: 40 hp (29.8 Kw) @ 5750 rpm
  • Outboard Weight: Electric: 204 lb (93 kg) 30/40 MH: 224 lb (112.7 kg) 30/40 ELPT: 235 lb (106.6 kg)
  • Recommended Fuel: Automotive Unleaded with a Minimum Pump Posted Octane Rating of 87
  • Recommended Oil: SAE 10W-30 viscosity oil for all temperatures.

Professional Workshop Service Manual & Technical Specifications

Mercury 30/40 FourStroke Outboard Motor Service Manual: Mercury Outboard Motor Repair Manual (1999) Data-Compendium

Service-Level: 1999 Mercury 30/40 FourStroke Models // Conceptual-Layout: Outboard Motor / Marine Engine Logic // Service-Level: Technical Specifications and Repair Procedures.

Mercury/Quicksilver Lubricants and Sealants

NOTE: See section 1A for lubricants and sealants chart.

Torque Chart

Fastener Location Diameter x Length (mm) Torque lb-in. lb-ft. Nm
Ignition
Coil Mounting Nuts M5 30 3.5
Coil Mount Plate Screw (Rear) M6 x 25 60 7
Coil Mount Plate Screw M6 x 30 75 8.5
Coil Plate Ground Screw M6 x 10 60 7
Spark Plug 12 mm 150 17
Charging & Starting System
Flywheel Cover Screws M6 x 25 75 8.5
Flywheel Nut N/A 116 157
Stator Screws (Electric) M5 x 30 85 9.5
Stator Screws (Manual) M5 x 25 85 9.5
Voltage Regulator Screws M6 x 40 75 8.5
Starter Motor Mount Bolts M8 x 45 21.5 29.5
Starter Cable Nut 1/4-20 60 7
Starter Motor Thru Bolts N/A 70 8
Battery Cable (+) Nut M6 60 7
Solenoid Plate Screw M6 x 14 45 5
Harness Retainer Screws M6 x 14 45 5
Wire Clamp Screw (Top of Block) M5 x 12 45 5
Cylinder Head
Cylinder Head Bolts (*) M9 x 95 34.5 47
Cylinder Head Bolts (*) M6 x 25 106 12
Baffle Plate Screws M4 x 10 Drive Tight
Valve Cover Screws M6 x 20 70 8
Valve Adjusting Nuts M6 120 13.5
Rocker Arm Shaft Screws M8 x 23 160 13
Driven Gear Screw M10 x 40 28 38
Cylinder Block/Crankcase
Crankcase Cover Bolts - Center (*) M8 x 82 22 30
Crankcase Cover Bolts - Outer (*) M6 x 35 106 12
Exhaust Cover Screws M6 x 35 106 12
Connecting Rod Bolts (*) Special 150 17
Oil Filter N/A 70 8
Oil Filter Nipple N/A 29.5 40
Powerhead Mounting Bolts (*) M8 x 110 33 44.5
Lifting Eye Screw M8 x 35 29 39.5
Oil Pressure Switch N/A 75 8.5
Oil Galley Plug 1/8-27 Pipe Plug 80 9
Oil Galley Plug 3/4-14 Pipe Plug 30 40.5
Oil Galley Plug 1/2-14 Pipe Plug 30 40.5

*NOTE: Two Step Torque - See appropriate section of component for details.

Reference chapters include Section 1B - Maintenance, Section 1C - General Information, Section 2A - Ignition, Section 2B - Charging & Starting System, Section 2C - Timing, Synchronizing, & Adjusting, Section 2D - Wiring Diagrams, and Section 3A - Fuel Pump.

This professional Mercury outboard motor service manual provides comprehensive procedural information for the 30/40 FourStroke models. Coverage includes detailed specifications, ignition system diagnostics, charging and starting system troubleshooting, carburetor adjustments, and wiring diagrams. Procedures are outlined for fuel pump maintenance, electrical system checks, and engine timing. This manual is intended for mechanics and service personnel familiar with outboard motor servicing.

This service manual provides specific technical data and procedures for servicing Mercury outboard motors, ensuring proper operation and longevity. It includes information on maintaining the ignition, charging, and fuel systems, as well as guidance on carburetor synchronization and idle speed adjustments. Torque specifications are provided for various components to ensure correct assembly and performance.

FAQ

Assess the **critical** calibration settings for the ignition system. keyboard_arrow_down

10° ATDC at idle (800 rpm) and 28° BTDC at WOT (6000 rpm) are the specified ignition timing specifications.

What components have **required** clearance measurements? keyboard_arrow_down

Valve clearance specifications are detailed for both Intake and Exhaust valves, with specific measurements provided in Section 2A-Ignition, page 2A-21, which covers the Engine Coolant Temperature (ECT) Sensor.

Confirm the **specified** torque specifications for the starter motor mounting screws. keyboard_arrow_down

22 lb. ft. (29 N·m) is the specified torque for the starter motor mounting screws (M8 x 45) when securing the starter to the block.

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Reviews (2)

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New
The manual is incredibly detailed and easy to follow. I had a few questions during the download process, but support was super responsive and helpful!
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This service manual has been a lifesaver for my Mercury outboard. Downloading was smooth, and customer service answered my queries quickly. Highly recommend!