Mercury 305 CID - Thunderbolt IV; Alpha Drive - All Engines with Ignition Module Mounted on Exhaust Elbow

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WIRING DIAGRAMS - 4F-190-823225--1 1096

Thunderbolt IV

Alpha Drive - All Engines With Ignition Module Mounted On Exhaust Elbow

50843

A. Ignition System C. Audio Warning System

B. Starting and Charging System D. Instrumentation System

Main Page

Important Information 1 a8
- Marine Engines1
- Replacement Parts3
- Table of Contents8
- Introduction9
- How to Use this Manual9
  - Page Numbering9
- How to Read Parts Manual10
- Directional References11
- Engine Rotation11
- Propeller Information12
- Water Testing New Engines12
- Boat and Engine Performance12
Important Information 1 B17
- Maintenance Schedules18
- Tune-Up Specifications24
- Tune-Up Specifications (Gen + Engines Only)27
  - Fluid Capacities28
- All Models29
  - 20-Hour Break-In Period29
  - After Break-In Period29
- Fuel, Oil, Fluid, and Coolant Specifications29
- Changing Oil and Filter32
- Maintaining Crankcase Oil Level32
  - Overfilled Engine Crankcase32
  - Checking Engine Oil Level/Filling32
- Maintaining Power Steering Pump Fluid Level33
  - With Engine Warm33
  - With Engine Cold33
- Filling and Bleeding Power Steering System 1B-1734
- Flushing Cooling System34
  - MCM Stern Drive35
  - MIE Inboard36
- Maintaining Closed Cooling Coolant Level34
- Maintaining Transmission Fluid Level37
- Lubrication38
- Audio Warning System42
  - Maintenance 1B-2542
- Cold Weather or Extended Storage42
Important Information 1 C60
- Precautions61
- Spark Plug Analysis62
  - Normal Condition62
  - Chipped Insulator62
  - Wet Fouling (Oil Deposits)62
  - Cold Fouling63
  - Overheating63
  - High Speed Glazing63
  - Scavenger Deposits63
  - Pre-Ignition Damage64
  - Reversed Coil Polarity64
  - Splashed Deposits64
  - Mechanical Damage64
- Used Spark Plug Analysis62
- Poor Boat Performance And/Or Poor Maneuverability65
- Improper Full Throttle Engine RPM66
  - RPM too High66
  - RPM too Low66
- Engine Cranks over but will Not Start or Starts Hard67
  - Important Information67
  - Testing Thunderbolt IV HEI System68
  - Testing Thunderbolt V Ignition System69
  - Fuel System Rich70
  - Fuel System Lean70
  - Miscellaneous70
- Charging System Inoperative71
  - Noisy Alternator71
- Engine will Not Crank over71
- Instrumentation Malfunction72
- Radio Noise72
- Poor Fuel Economy73
- Carburetor Malfunctions74
- Engine Runs Poorly at Idle75
- Engine Runs Poorly at High RPM76
- Engine Acceleration Is Poor77
- Troubleshooting with Vacuum Gauge77
- Engine Noise78
  - Important Information78
  - Valve Cover Area78
  - Cylinder Area79
  - Camshaft Area79
  - Crankshaft Area80
  - Miscellaneous81
- Oil Pressure82
  - Low Oil Pressure83
  - High Oil Pressure83
- Excessive Oil Consumption84
- Water in Engine85
  - Important Information85
  - Water on Top of Pistons85
  - Water in Crankcase Oil86
- Engine Overheats (Mechanical)86
- Engine Overheats (Cooling System)87
  - Insufficient Water Flow from Belt Driven Seawater Pickup Pump88
- Power Steering89
  - Poor, Erratic, or no Assist89
  - Noisy Pump90
  - Fluid Leaks90
- Troubleshooting Silent Choice Exhaust Silencer System91
Removal and Installation 293
- Tools/Lubricants/Adhesives/Sealants94
- Torque Specification94
- Removal95
  - Engine Removal95
- Installation96
  - Engine Installation/Alignment96
  - Engine Connections98
Removal and Installation 2104
- Removal106
  - Engine Removal106
- Installation108
  - Engine Installation/Alignment108
  - Engine Connections113
Removal and Installation 2121
- Tools/Lubricants/Adhesives/Sealants122
- Torque Specifications122
- Removal123
  - Engine Removal123
- Installation124
  - Engine Installation/Alignment124
  - Engine Connections127
Removal and Installation 2136
- Removal138
  - Engine Removal138
- Installation140
Removal and Installation 2155
- Lubricants/Sealants156
- Torque Specifications156
- Removal157
  - Engine Removal157
- Installation158
- Fuel Supply Connections162
- Attaching/Adjusting Reversed Attachment Morse Shift Cables170
Removal and Installation 2174
- Lubricants/Sealants175
- Torque Specifications175
- Removal176
  - Engine Removal176
- Installation177
Engine190
- Lubricants/Sealers/Adhesives196
- Engine Specifications197
  - L / 305 CID / 5.7L / 350 CID Engine199
  - Gen + Engine Specifications206
- General207
  - Engine Identification207
  - Cylinder Head Identification208
  - Engine Rotation208
  - Crankshaft208
  - Piston and Connecting Rods208
  - Camshaft and Drive209
  - Cylinder Head209
  - Valve Train209
  - Intake Manifold209
  - Lubrication System209
- Bearing Failures211
- Piston Failures212
  - Pre-Ignition212
  - Detonation213
- Engine Mounts214
- Intake Manifold216
  - Cleaning and Inspection216
  - Installation217
- Rocker Arm Cover216
  - Removal216
  - Installation216
- Rocker Arm/Push Rod219
  - Removal219
  - Cleaning and Inspection219
  - Installation219
- Valve Adjustment219
  - Engine Stopped219
  - Engine Running220
- Hydraulic Valve Lifters (Flat and Roller Lifter)221
  - Locating Noisy Lifters221
  - Removal222
  - Cleaning and Inspection222
  - Installation222
- Valve Stem Oil Seal/Valve Spring222
  - Removal - Head Installed222
  - Valve Assembly (Exploded View)224
  - Installation - Head Installed224
- Cylinder Head224
  - Removal224
  - Cleaning and Inspection225
  - Installation225
- Cylinder Head and Valve Conditioning226
  - Disassembly226
  - Cleaning226
  - Inspection226
  - Valve Guide Bore Repair227
  - Valve Springs - Checking Tension228
  - Rocker Arm Stud Replacement229
  - Valve Seat Repair229
  - Valve Grinding230
  - Reassembly230
    - Dipstick Specifications233
    - All Engines233
- Oil Pan234
  - Removal234
  - Installation234
- Oil Pump236
  - Removal236
  - Disassembly236
  - Cleaning and Inspection237
  - Reassembly237
  - Installation237
- Torsional Damper238
  - Removal238
  - Installation238
- Crankcase Front Cover239
  - Removal240
  - Cleaning and Inspection240
  - Installation240
- Crankcase Front Cover/Oil Seal239
  - Oil Seal Replacement (Without Removing Front Cover)239
- Flywheel240
  - Inspection241
  - Installation242
- Rear Main Oil Seal243
  - Removal243
  - Cleaning and Inspection243
  - Installation244
- Rear Main Oil Seal Retainer244
  - Removal244
  - Cleaning and Inspection244
Electrical Systems267
- Battery268
  - Battery Cable Recommendations268
- Identification268
- Lubricants/Sealants268
- Replacement Parts Warning268
- Torque Specifications268
- Direct Drive Starter Motor269
  - Specifications269
- Lubricants/Sealants269
- Positive Current Flow269
- Torque Specifications269
- Starting System Components270
- Starter Motor (Exploded View)271
- Periodic Inspection272
- Starter Motor Repair272
  - Removal272
  - Solenoid Switch272
  - Starter Motor Disassembly274
  - Cleaning and Inspection274
  - Armature Tests275
  - Field Coil Tests275
  - Loose Electrical Connections276
  - Turning the Commutator276
  - Reassembly276
  - Clearances277
  - Installation278
- (PG200, PG250 and PG260) Starter Motor279
  - Specifications279
  - Maintenance280
  - Testing280
  - Storage280
- Permanent Magnet Gear Reduction279
- Standard Starter Slave Solenoid281
  - Testing/Replacement281
- Starting System Components282
- Description283
- Positive Current Flow283
- And PG 250 Starter Motor (Exploded View)285
- And PG 250 Starter Motor Repair286
  - Removal286
  - Disassembly287
  - Cleaning and Inspection289
  - Armature Tests289
  - Armature Bearing (Commutator End)289
  - Gear Bearing290
  - Shaft Assembly Bearing290
  - Drive End Housing Bearing290
  - Brushes and Brush Holder291
  - Reassembly292
  - Installation294
- Periodic Inspection286
- Solenoid Switch286
- PG 260 Starter Motor295
  - Exploded View295
- Periodic Inspection296
- PG 260 Starter Motor Repair296
  - Removal296
  - Disassembly297
  - Cleaning and Inspection299
  - Armature Tests300
  - Brushes and Brush Holder300
  - Reassembly302
  - Clearances305
  - Installation305
- Solenoid Switch296
Electrical Systems309
- For Information and Procedures on Trouble309
- Notice309
- Shooting, Refer to Section 1C309
- Specifications311
- Repair315
- Distributor Repair318
- Distributor Installation321
  - Engine Not Disturbed321
  - Engine Disturbed321
- Thunderbolt IV Ignition Timing322
- Thunderbolt V Ignition System323
  - Identification323
- General Description324
- Thunderbolt V Spark Control Graph325
- Circuit Description326
- Ignition System Wiring Diagram327
- Timing and Idle Adjustment Procedures328
- Troubleshooting Thunderbolt V Ignition329
Electrical System335
- Mando 55 and 65 Amp Alternator Identification336
- Replacement Parts Warning336
- Specifications336
- Tools/Sealants336
- Torque Specifications336
- Description337
- Precautions337
- Periodic Maintenance338
- System Components338
- Drive Belt Tension Adjustment339
  - V-Belt339
  - Serpentine Belt339
- Troubleshooting Tests (Alternator on Engine)340
- Alternator Repair346
- Installation355
- Battery Isolators356
  - Dual Battery Charging Systems Using a Battery Isolator356
- Battery Isolator357
Electrical System361
- Identification362
- Special Information362
  - Lighting Options362
    - Commodore and International Series362
    - QSI Series363
- Gauges363
- Senders366
- Switches370
- Audio Warning System372
Electrical Systems394
- Thunderbolt IV395
- EFI Engine Harness410
- Audio Warning System425
- Battery Meter Gauge425
- Cruiselog425
- Fuel Gauge and Sender425
- Clock426
- Oil Pressure Gauge426
- Water Temperature Gauge426
Fuel System428
- Identification429
- Replacement Parts Warning429
- Specifications429
- Tools / Lubricants / Sealants429
- Torque Specifications429
  - Fuel Supply Connections429
- Fuel Delivery System430
  - Recommendations430
- Precautions430
- Fuel System Components431
- Water Separating Fuel Filter435
  - Replacement436
- Sight Tube436
  - Inspection436
- Mechanical Fuel Pump437
  - Replacement437
- Testing Mechanical Fuel Pump437
Fuel System439
- Mercarb 2 BBL Carburetor440
- Exploded View441
- Identification443
- Important Service Information443
- Description444
- Maintenance445
- Precautions445
- Adjustments447
- Repair450
Fuel Systems468
- Carburetor Adjustment Specifications470
- Carburetor Specifications470
- Description471
- Maintenance471
  - Flame Arrestor471
  - Fuel Filter472
- Precautions471
- Adjustments473
- Repair478
Fuel Systems498
- Identification499
- Replacement Parts Warning499
- Tools499
  - Carburetor Adjustment Specifications501
- Torque Specifications499
- Description502
- Precautions502
- Important Service Information503
- Maintenance505
  - Flame Arrestor505
  - Fuel Filter506
- Adjustments507
- Idle Speed and Mixture Adjustments510
  - Thunderbolt IV Equipped Engines510
  - Thunderbolt V Equipped Engines512
- Repair513
Fuel Systems539
- General Information542
- Electronic Control Module (ECM) and Sensors551
- ECM Connector and Symptom Charts568
- Diagnostic Circuit Check592
Fuel Systems728
- Identification729
- Replacement Parts Warning729
- Special Tools729
- Torque Specifications729
- Carburetor Adjustment Specifications730
- Carburetor Specifications730
- Engine Specifications730
- Description731
- Special Notes731
- Precautions733
- Maintenance734
- Troubleshooting735
  - Checking Ported Vacuum Switch735
    - And Carburetor Vacuum Circuit for Correct Operation735
- Service Procedures736
- Emissions Testing742
- Test Equipment742
Cooling System745
- MCM 350 CID / 5.7L746
- Seawater Inlet Recommendations747
- Seawater Pickups748
  - Thru-Hull Mounted748
  - Transom Mounted748
- Sea Strainer (Quicksilver)749
  - Removal749
  - Installation750
- Stern Drive Unit Seawater Pickup Pump Output Test751
- Stern Drive Unit Seawater Pickup Pump Repairs752
- Water Circulating Pump Replacement752
- Flushing Seawater Cooling System753
- Thermostat754
- Draining Seawater Cooling System757
- Auxiliary Hot Water Heater Installation763
- Water Flow Diagrams765
Cooling System774
- 305/350 CID / 5.0L/5.7L775
- Water Flow Diagrams776
  - Engines with Coolant Flow Thru Exhaust776
  - Engines with Raw Water Flow Thru Exhaust Manifolds777
- Description778
- Seawater Pickup Pump (if Equipped)778
- Pressure Cap Maintenance791
- Heat Exchanger Repair792
- Testing Closed Cooling System792
- Thermostat795
- Changing Coolant800
- Cleaning System801
- Filling Closed Cooling Section806
Exhaust System824
- Exhaust System Requirements825
- Exhaust Tube Requirements827
Exhaust System845
- Lubricants/Sealants/Adhesives846
  - Shutter Replacement846
  - Component Replacement847
- Torque Specifications846
- Below Swim Platform Exhaust Pipe Kit848
  - Modifying Swim Platform Exhaust Pipe, if Required849
- Thru-Transom Exhaust848
  - Shutter Replacement848
  - Component Replacement848
- Silent Choice Exhaust System849
- Exhaust Muffler Kit852
Drives857
- Velvet Drive In-Line (71C and 72C) Specifications858
- Important Information860
- Checking Transmission Fluid Level861
- Shift Cable Adjustment861
- Changing Transmission Fluid862
  - Draining Transmission862
  - Filling Transmission863
- Removal and Installation864
- Pump Indexing865
- Pressure Test866
- Shift Lever Installation866
- Transmission Repair866
Drives870
- Transmission Fluid Capacities872
- Transmission Fluid Specification872
- Transmission Output Shaft Rolling Torque872
- Transmission Pressure Specifications872
- Important Information873
- Checking Transmission Fluid Level874
- Shift Cable Adjustment874
- Changing Transmission Fluid875
  - Draining Transmission875
  - Filling Transmission876
- Removal and Installation877
- Pump Indexing878
- Pressure Test879
- Shift Lever Installation879
- Transmission Repair879
  - V-Drive879
Drives883
- Specifications885
- General886
- Shift Cable Installation and Adjustment886
- Checking Transmission Fluid Level891
- Draining Transmission892
- Filling Transmission892
- Transmission Removal893
- Transmission Installation894
- Transmission Repair895
- Functional Test929
Drives933
- Tools/Lubricants/Sealants934
- Torque Specifications934
- (MCM Stern Drive Models)935
  - Repair937
  - Replacement Drive Shafts937
- Repair (MCM Stern Drive Models)935
- Installation938
- Bearing Support Repair (MCM Stern Drive Models)939
- Propeller Shaft (MIE Inboard Models)942
Power Steering948
- (Exploded View)950
- Power Steering Pump and Components950
- Serpentine Belt Routing951
- Important Service Information952
  - Pump Pulley Replacement952
- Belt Adjustment953
  - V-Belt953
  - Serpentine Belt Adjustment953
- Checking Pump Fluid Level953
- Filling and Air Bleeding System953
- Testing and Repair953
- Pump Assembly954
- Hydraulic Hoses and Fluid Cooler955
  - Valve)955
  - Low Pressure Hose (Control Valve-To-Cooler)958
- Mounting Bracket955
- Priority Valve Kit (79691A1) Information960

Mercury 305 CID - Thunderbolt IV; Alpha Drive - All Engines with Ignition Module Mounted on Exhaust Elbow

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