Mercury outboard switch box troubleshooting

Johnson Evinrude Parts. Mercury Mariner Parts. Force Ignition Parts. Chrysler Ignition Parts.

Outboard Motors

Yamaha Ignition Parts. Ignition Switches. Outboard ignition parts for Mercury Mariner outboard motors. Power pack, stator, timerbase, regulator. Index - Page 2. Intermittent Firing: This problem can be very hard to isolate.

mercury outboard switch box troubleshooting

A significant difference in the readings can help pinpoint a problem where there is no other easy means to do it. If the packs totally lose fire on all cylinders, the stator could be sending voltage spikes into the pack destroying it. Any sign of rubbing on the outside of the stator indicate problem in the upper or lower main bearings. Cracked trigger or outer magnets can cause everything from misfiring to no fire at all.

Loose flywheel magnets can be dangerous, check the tightness of the bonding adhesive. An easy check is to disconnect the stator leads to the rectifier Make sure to insulate them and retest. Engines with S.

Mercury power pack/switch box fix - with bonus footage

If the engine is NOT overheating, this can be caused by a temperature sensor failing early. Make sure that all of the Tan wires are located as far as possible from the spark plug wires. Also check the blocking diode in the engine harness.

If more than one cylinder is not firing: replace BOTH switch boxes unless you can pin the problem down to the trigger. You should readohms on stock switch boxes and 9, ohms on racing switch boxes.

Mercury Outboard Ignition Switch Wiring Diagram

Any problem on the bias circuit and BOTH switch boxes must be replaced as a set. No Fire on 1, 3, 5 or 2, 4, 6: Swap the stator leads from one switch box to the other. If the problem moves, replace the stator. If the problem remains on the same cylinders, replace the switch boxes. If the stator is replaced and the problem is still there, try another flywheel. If all the cylinders are now firing, replace the switch box that was firing all three cylinders originally.

To verify this condition, swap the trigger leads around of the switch box that was firing all three cylinders originally. If the misfire moves to another cylinder, the switch box is bad.Your outboard stator is the "powerhouse" of your outboards ignition system. Most Mercury Outboard Stators perform two important functions 1. They provide voltage to your switchbox or CDM's. They charge your vessel's battery s.

A faulty or failing stator can cause one or more symptoms. Engine fails to run and has no spark. Engine is hard to start especially after sitting from a run. Engine is low on power or has a "miss". Engine stalls frequently. Engine does not recharge the vessel's battery s. Vessel's battery s keep going dead or have too low of voltage. Stators fail! Stators can fail for one or more of the following reasons. An engine that is running too hot will "overheat" the stator.

mercury outboard switch box troubleshooting

Bad batteries, bad battery cables, poor connections and wrong style of batteries can cause the stator to get too hot from attempting to charge the batteries. The procedure for performing an accurate diagnosis on your stator will depend on what model engine you have.

In general, there are two types of tests. Voltage Output Test. Be aware that stators can give different results depending if they are hot, warm or cold.

Some failures only show up clearly after the motor has reached operating temperature. Just because a stator passes the "Ohms Test" does not mean it is good.

If a stator fails the Ohms Test, it is bad. Keep in mind that a bad stator might not be your only problem. A bad stator can cause a switchbox to fail. Mercury Marine recommends that the switchbox s be replaced in the event of a stator failure.

This is because a bad stator can weaken or ruin a good switchbox. It is often the case that the old switchbox s fail shortly after a new stator has been installed. To perform the Ohms Test you will need a good ohm meter. Damage, Injury or Death can result if the engine cranks or starts while you are near the flywheel.Mercury Marine is an international motor boat company based in Lake Forest, Illinois, providing motors for private, commercial and government craft.

Mercury produces an extensive line of outboard motors. Like all mechanical equipment, Mercury motors can exhibit issues, ignition problems being some of the most worrisome. Many ignition problems stem from electrical issues, but there are a few general troubleshooting tasks you should perform.

mercury outboard switch box troubleshooting

Check that there is plenty of gas in the gas tank and that all fluid levels are at the right level. Make sure that all wires are connected properly.

If there is no start from the engine, there may be no spark present. Check that the spark plug for the engine is free of decay and is clean. If there is any water on the spark plug, check for leaks. These are the shorting and short circuit wires. Removing these allows you to troubleshoot the kill circuit. If the engine starts when these wires are disconnected, then the shorting system is faulty.

If the engine does not start after disconnecting these wires, check the purple wire, which is the ignition switch wire, for damage and that it is secured properly. This will change the engine starting cylinder. If the problem persists in the new cylinder, the stator is bad and needs to be changed. Share It. Photo Credits.Many people find themselves troubleshooting a 25 HP Mercury boat motor after the boat has not been used for several months.

By understanding how to troubleshoot the motor, a person can also understand what kinds of things they should avoid doing that may have damaged the motor in the first place. Concentrate on understanding if there is a spark in the motor and if the fuel is reaching the motor. These are the two things that are most often the culprits when there is a problem with a 25 HP Mercury boat motor.

Although problems could come from other sources, it is unlikely. Troubleshoot the ignition by using a spark detector.

Auto supply stores sell these detectors. They do not need to be made specifically to detect the spark in a 25 HP Mercury boat motor. A generic spark detector will do. Crank the motor to see if there is a spark.

Remember to check for a spark on both of the 25 HP Mercury boat motor cylinders. If there is a spark, there is a good chance that the ignition is not the problem. Check the black and yellow wires if there is no spark. This can be done by removing it from the switchbox and replacing it with a new wire. If there is a spark after replacing the wire, the problem has been solved. Troubleshoot the carburetor, if there is still no spark, by looking and feeling for any sticky gunk that is inside of the carburetor.

Too much of this gunk can cause the carburetor to overflow. When an overflow in a 25 Hp mercury boat motor occurs, the motor can become flooded and make it difficult for valves to close. Remove the fuel cap to drain the old fuel. Soak the carburetor in a carburetor-cleaning solution.

How to Troubleshoot a Mercury Outboard Engine

Do not attempt to remove the main jet from the carburetor until the carburetor has soaked for at least an hour to remove the stickiness. Remove the main jet from the carburetor by sticking a flathead screwdriver through a hole in the carburetor to dislodge the jet. Do not attempt to open the fuel jet with a piece of wire or metal. Instead, rinse and soak the jet and then spray the jet with compressed air.Repair Manuals. Parts Depts. Chrysler Outboard. Force Outboard. Johnson Evinrude.

Mercury Mariner. Mercruiser Stern Drive. Yamaha Outboard. Boating Classifieds NEW! Manufacturer Links. Page 19 - Index - Page NOTE: These engines sometimes develop a problem where you only have one cylinder firing.

This can be caused by the flywheel magnets coming loose and shifting around until they touch. If only one cylinder is firing, remove the flywheel and check the magnets to see if they are tightly bonded.

If the ignition system now fires, the kill circuit has a problem. Check the stator resistance and DVA output:. Check the trigger resistance and output:. Check the reading on the switch box terminal AND on the ignition coil terminal. You should have a reading of at least V or more at both places. If the reading is low on one cylinder, disconnect the green wire from the ignition coil for that cylinder and reconnect it to a load resistor.

If the reading is now good, the ignition coil is likely bad. A continued low reading indicates a bad power pack. NOTE: This system uses a timing advance circuit inside the switch box to control timing.

The black stator wire is NOT tied directly to ground inside the pack.Backed by decades of innovation and leadership, Mercury outboards are built to go the distance, delivering legendary performance driven by forward-thinking technology.

The ultimate combination of smooth and quiet operation, refined power, and effortless control. Fly over shallow-water obstacles with the greatest of ease. The ultimate for convenience -- quiet, capable and lightweight. When you make the best marine products in the world, you want the best dealers behind them. This website uses cookies to enhance and improve your browsing experience.

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mercury outboard switch box troubleshooting

The best products have the best dealers. Find your dealer. Sign up to receive the latest tips, promotions and news from Mercury. Sign Up For Email Enter your email address to receive the latest tips, promotions and news from Mercury.Outboard boat motors are notorious for problems. To troubleshoot the engine, go through a series of checks for specific issues that can occur and fix as needed.

The most common problem with both two- and four-stroke engines begin with the fuel system. Given this reality, keep a couple of oars handy for if the engine fails while you're out on the water. It also helps to have a citizen's band radio aboard the boat or a cell phone if there is service in the area to contact someone for help if needed.

Mercury Marinebased in Wisconsin, has been making Mercury outboard motors in two- and four-stroke versions ranging from 2. If you have a two-stroke outboard motor, you must add oil to the fuel to lubricate the engine. Four-stroke engines don't need the oil in the engine and are much cleaner machines overall. All two-stroke engines require that you add a specific oil to the gasoline.

The oil-to fuel ratio depends on the requirements of the specific motor. The oil protects and lubricates the engine as well as ensuring a long- life.

If you do not mix the oil according to the correct ratio -- which could beor depending on your motor -- you will have problems such as:. To correct this, empty the fuel tank of all oil. In a clean can containing a gallon of gas, pour in the correct amount of oil.

For example, if you require a ratio, each gallon of gas requires 4 ounces of the right oil for the motor mixed in. Foradd 3. Remove and clean the spark plug and replace it before pouring the gas back into the fuel tank. Improperly mixed gasoline tends to foul the spark plug as well. Some engines -- not the pull-start kind -- have a battery that starts it. If your engine has a battery, make sure it is charged up before use; verify the battery connections are clean -- as corroded connections can keep a Mercury outboard from starting.

Outboard motors require that you start them up and hold the gas until they can idle on their own. Once the motor idles on its own, it is warm enough to operate. Stalling, power loss or excessive vibration generally indicates one or more of the following, depending on the specific problem :. A fouled propeller requires turning the engine off and cleaning the debris from the propeller. But when the motor runs fine, but the boat doesn't go anywhere, it's likely the propeller isn't spinning due to a broken shear pin.


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