Do you have a question about the 25 EFI and is the answer not in the manual?
Questions and answers
Christina Newman
April 4, 2025
Where to find the serial numer
1 comments:
Mr. Anderson
April 4, 2025
The serial number on a Mercury 25 EFI is located on the outboard motor.
This answer is automatically generated
Alex
February 2, 2025
Have no spark and have new stator and new trigger, rectifier, new coils and new spark plugs. I have checked remote kill switch and ohmed out good, and even disconnected and still no spark. The wire from remote to engine plugs is black/yellow, but not sure what color it changes to on the engine side. I **** at a lost
1 comments:
Mr. Anderson
February 10, 2025
Possible causes of no spark in a Mercury 25 EFI after replacing the stator, trigger, rectifier, coils, and spark plugs include:
1. Incorrect or Loose Ignition Coil Installation – Ensure ignition coils are securely installed onto the spark plugs. 2. Wrong Spark Plugs – The engine may not run or spark correctly if incorrect spark plugs are used. 3. Faulty Connectors or Wiring – Inspect connectors for corrosion, loose wires, or pushed-back pins. Ensure all connectors are properly seated. 4. Damaged Wiring Harness – Look for pinched, cut, or chafed wires in the harness. 5. PCM or Sensor Issues – If all cylinders exhibit similar symptoms, a sensor or harness input to the PCM may be faulty. 6. Faulty Grounds or Loose Ring Terminals – Secure all ground connections and ring terminals.
If the issue persists, reviewing the PCM fault history using the CDS may help diagnose the problem.
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25 / 30 EFI & 25 EFI Jet S E RV I C E MA N U A L...
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NOTE: Indicates information that helps in the understanding of a particular step or action. This manual has been written and published by the Service Department of Mercury Marine to aid our dealers’ mechanics and company service personnel when servicing the products described herein. We reserve the right to make changes to this manual without prior notification.
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Cleanliness and Care of Product A Mercury Marine power product is a combination of many machined, honed, polished, and lapped surfaces with tolerances measured in the ten thousands of an inch/mm. When any product component is serviced, care and cleanliness are important. It should be understood that proper cleaning and protection of machined surfaces and friction areas is a part of the repair procedure.
Some accessories not manufactured or sold by Mercury Marine are not designed to be safely used with your outboard or outboard operating system. Acquire and read the installation, operation and maintenance manuals for all your selected accessories.
Use a Mercury Precision or Quicksilver accessory (or equivalent) flushing attachment. IMPORTANT: The engine must be run during flushing in order to open the thermostat and circulate water through the water passages.
Remove the fill cap and check the fluid level. The fluid level should be even with the bottom of the fill hole. Add Quicksilver or Mercury Precision Lubricants Power Trim and Steering Fluid. If not available, use automotive (ATF) automatic transmission fluid.
Gearcase Lubricant Capacity Gearcase lubricant capacity is approximately 350 ml (11.8 fl. oz.). Gearcase Lubricant Recommendation Mercury or Quicksilver Premium or High Performance Gear Lubricant. Checking Lubricant Level and Refilling Gearcase Place outboard in a vertical operating position. Remove vent plug.
Lubricate all outboard components listed in the Inspection and Maintenance Schedule, preceding. • Touch‑up any paint nicks. • Spray Quicksilver or Mercury Precision Lubricants Corrosion Guard on external metal surfaces (except corrosion control anodes). Tube Ref No. Description Where Used Part No.
30% relative humidity, at 25 °C (77 °F) temperature, and a barometric pressure of 29.61 inches of mercury. Summer conditions of high temperature, low barometric pressure, and high humidity all combine to reduce the engine power.
The boat manufacturer and the selling dealer are responsible for equipping the power package with the correct propeller. Refer to Mercury Marine's web page https://www.mercurymarine.com/en/us/propellers/selector/#/step‑one. Select a propeller that will allow the engine power package to operate at or near the top end of the recommended WOT operating RPM range with a normal load.
Using Reformulated (Oxygenated) Gasoline (USA Only) Reformulated gasoline is required in certain areas of the USA and is acceptable for use in your Mercury Marine engine. The only oxygenate currently in use in the USA is alcohol (ethanol, methanol, or butanol).
IMPORTANT: When operating a Mercury Marine engine on gasoline containing methanol or ethanol, do not store the gasoline in the fuel tank for long periods. Cars normally consume these blended fuels before they can absorb enough moisture to cause trouble;...
Allow a minimum of one hour drying time and no more than one week before the top coat application. Use Ditzler Urethane DU9300 for Mercury Black, DU34334 for Mariner Grey, DU35466 for Force Charcoal, DU33414M for Sea Ray White, and DFHS 37372H for Verado Silver. Catalyze all five colors with Ditzler DU5 catalyst mixed 1:1 ratio.
Selecting Accessories for Your Outboard Genuine Mercury Precision or Quicksilver Accessories have been specifically designed and tested for your outboard. These accessories are available from Mercury Marine dealers. IMPORTANT: Check with your dealer before installing accessories. The misuse of approved accessories or the use of nonapproved accessories can damage the product.
Outboard Installation Some accessories not manufactured or sold by Mercury Marine are not designed to be safely used with your outboard or outboard operating system. Acquire and read the installation, operation and maintenance manuals for all your selected accessories. Low Permeation Fuel Hose Requirement Required for outboards manufactured for sale, sold, or offered for sale in the United States.
Installing Jet Outboard Mercury Marine Validated Engine Mounting Hardware IMPORTANT: Mercury Marine provides validated fasteners and installation instructions, including torque specifications, with all of our outboards so they can be properly secured to boat transoms. Improper installation of the outboard can cause performance and reliability issues that can lead to safety concerns.
Some accessories not manufactured or sold by Mercury Marine are not designed to be safely used with your outboard or outboard operating system. Acquire and read the installation, operation and maintenance manuals for all your selected accessories.
The ECM is designed that if a sensor fails, the ECM will compensate so that the engine does not go into an over‑rich condition. Because of this, disconnecting a sensor for troubleshooting purposes may have no noticeable effect. The CDS has been developed specifically to help technicians diagnose and repair Mercury Marine 2 and 4 cycle engines. CDS G3 Diagnostic Tool Kit 8M0114141 Attach the 84‑899150T01 diagnostic cable to the ECM diagnostic port and attach the 84‑822560A7 adapter to the...
Replacement Parts WARNING Avoid fire or explosion hazard. Electrical, ignition, and fuel system components on Mercury Marine products comply with federal and international standards to minimize risk of fire or explosion. Do not use replacement electrical or fuel system components that do not comply with these standards. When servicing the electrical and fuel systems, properly install and tighten all components.
The ECM is designed that if a sensor fails, the ECM will compensate so that the engine does not go into an over‑rich condition. Because of this, disconnecting a sensor for troubleshooting purposes may have no noticeable effect. The CDS has been developed specifically to help technicians diagnose and repair Mercury Marine 2 and 4 cycle engines. CDS G3 Diagnostic Tool Kit...
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EPA Emission Regulations All new 1998 and newer outboards manufactured by Mercury Marine for operation in the USA, are certified to the United States Environmental Protection Agency as conforming to the requirements of the regulations for the control of air pollution from new outboard motors.
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Cut and remove a "V" notch through the month of engine manufacture before installing the new label. The month of manufacture can be found on the old label. If the label is missing or the date code illegible, contact Mercury Marine Technical Service for assistance.
Remove the fill cap and check the fluid level. The fluid level should be even with the bottom of the fill hole. Add Quicksilver or Mercury Precision Lubricants Power Trim and Steering Fluid. If not available, use automotive (ATF) automatic transmission fluid.
Gearcase Lubricant Capacity Gearcase lubricant capacity is approximately 350 ml (11.8 fl oz). Gearcase Lubricant Recommendation Mercury or Quicksilver Premium or High Performance Gear Lubricant. Checking Lubricant Level and Refilling Gearcase Place outboard in a vertical operating position. Remove vent plug.
Place a block of wood between the propeller blade and the anti‑ventilation plate. To aid in the future removal of the propeller, liberally apply to the propeller shaft splines with one of the following Mercury/ Quicksilver products: Tube Ref No.
Need help?
Do you have a question about the 25 EFI and is the answer not in the manual?
Questions and answers
Where to find the serial numer
The serial number on a Mercury 25 EFI is located on the outboard motor.
This answer is automatically generated
Have no spark and have new stator and new trigger, rectifier, new coils and new spark plugs. I have checked remote kill switch and ohmed out good, and even disconnected and still no spark. The wire from remote to engine plugs is black/yellow, but not sure what color it changes to on the engine side. I **** at a lost
Possible causes of no spark in a Mercury 25 EFI after replacing the stator, trigger, rectifier, coils, and spark plugs include:
1. Incorrect or Loose Ignition Coil Installation – Ensure ignition coils are securely installed onto the spark plugs.
2. Wrong Spark Plugs – The engine may not run or spark correctly if incorrect spark plugs are used.
3. Faulty Connectors or Wiring – Inspect connectors for corrosion, loose wires, or pushed-back pins. Ensure all connectors are properly seated.
4. Damaged Wiring Harness – Look for pinched, cut, or chafed wires in the harness.
5. PCM or Sensor Issues – If all cylinders exhibit similar symptoms, a sensor or harness input to the PCM may be faulty.
6. Faulty Grounds or Loose Ring Terminals – Secure all ground connections and ring terminals.
If the issue persists, reviewing the PCM fault history using the CDS may help diagnose the problem.
This answer is automatically generated