Why the outboard motor is Slowly Gaining Grows and How to Fix It

The situation of outboard motors not pulling or reluctantly responding to the handle of gas, familiar to many aqueous motorists. Instead of confident getting on plane, you hear a strained roar, and the speed is barely more than 10-15 kilometers per hour, it is not just discomfort, but also a potential security threat, especially if you need to quickly get away from the wave or obstacle.

The reasons for this behavior of the engine can be hidden in elementary things, such as fuel quality, and in serious mechanical malfunctions. transmission It's often solved by rapid prevention, which can be done right on the shore, but sometimes it requires a complete defect in the workshop, and it's important to be able to distinguish symptoms so that you don't waste time and money on replacing the nodes.

In this article, we will take a detailed look at all the stages of diagnosis from simple to complex, you will learn how to check the fuel supply system, assess the condition. spark plug And we can understand when the problem is in the boat or the propeller, and if you take a good approach, you can get the engine back to speed and save money on expensive repairs.

Primary Diagnosis and External Factors

Before climbing into the inside of the engine, you need to exclude the influence of external factors. Often drivers forget that the specifications of the vessel directly affect the work. engineAn algae-draining, improper loading or damaged propeller creates an excess drag that the motor cannot overcome even at full speed.

Notice the behavior of the boat, if it's a hard climber and it's pecking its nose, it may be a violation of the balance of the cargo. anticavitationalIf it is too high or low relative to the water level, the efficiency of the rotor stop drops and the motor runs idle or overloaded.

Check lower unit for coiled fishing nets or fishing lines. Even a thin thread caught on a gland can significantly slow the rotation of the propeller. Visual inspection of the propeller is mandatory: chips, bullies or deformation of the blades disrupt the fluid dynamics, forcing the engine to run to the limit.

• 🚤 Check the cleanliness of the bottom and the absence of algae fouling.
• ⚖️ Make sure that the weight of passengers and cargo is properly distributed.
• 🔧 Examine the screw blades for damage and windings.
• 🌊 Evaluate the position of the anti-cavitation plate relative to the waterline.

⚠️ Attention: Never try to clean the screw of a winding line or grass on the engine running or when the gear is on. This can lead to serious injuries to the hands.

Fuel supply system: from tank to carburetor

The most common reason why the engine doesn't get full speed is the banal "starvation." The fuel system is your motor's circulatory system, and any blockage here is critical. You should start with the fuel tank and the hoses. Make sure that the tank has fuel and the hose does not form air traffic jams.

The key element here is a fuel filter-sludge, and if it's filled with dirt, water or paraffin (in winter), the gasoline just doesn't come in the right amount. fuel pumpOn many two-stroke engines, it's a membrane pump that loses its elasticity over time and stops pumping fuel at the required pressure.

Carburetor engines often clog jelly. Small fractions of garbage or tar deposits from old gasoline block the channels. In this case, the engine can run on idles, but when you try to open the throttle will stall or choke. For four-stroke engines, the problem of pollution is relevant. fuel-nozzle or a fine filter.

If you use gasoline with an octane number below the recommended, detonation may occur. Electronics (or mechanics) will automatically limit the power to save the piston group from breaking. your model engine.

Air filter and intake system

Fuel combustion requires air, and it has to be abundant. If air is limited, the mixture becomes over-enriched, causing power to fall and smoke, first inspecting an air filter, on dusty dirt roads or in hot weather, it clogs faster.

Remove the air filter cover and assess its condition. If it's paper and blackened, it needs to be replaced. If it's spongy, it needs to be rinsed carefully in gasoline or a special cleaner and oiled. A dirty filter creates a vacuum that strangles the engine, preventing it from spinning above 3,000-4000 rpm.

Also check the condition of the petal valve(s) on two-stroke motors, if the petals are deformed, chipped or not fitting tightly, the filling of the cylinder with fresh mixture is disturbed, which leads to unstable operation and loss of traction at the bottom and top.

• 🌬️ Remove and inspect the air filter for dirt.
• 🧼 Wash the sponge filter or replace the paper element.
• 🔍 Check the petal valve for leakage and integrity.
• 🔩 Make sure the intake manifold is tight.

⚠️ Attention: Never start an engine without an air filter installed. Getting dust or sand into the cylinder will cause instant bullies and require major repairs.

Ignition and candle system

A spark must be powerful and timely. A weak spark cannot ignite a mixture under load when the piston compresses it with maximum force. First, twist the candles. The color of the candles will tell you a lot: black nagar will indicate a rich mixture, white will indicate a poor one, and brown or brick shade indicates normal operation.

Check the gap between the candle electrodes. Too much gap will require a high voltage to break down, which the coil may not give out. Too small will give a weak spark. The optimal gap is usually 0.7-0.8 mm, but it is better to check the manual for the first time. model engine.

Don't forget to check the high-voltage wires and caps. Oxidation of contacts inside the cap or failure of wire insulation (especially in wet weather) leads to loss of energy. flash-sensor If it's faulty or oxidized, it can spark and reset ignition when it vibrates.

Candle condition	The color of nagara	Probable cause	Action.
Normal.	Bricky/Light brown	The mixture's normal.	Continue operation
Fresh.	Black, wet, buttery	Lots of oil/rich mixture	Replace the candle, check the carburetor
Overheated	White, melted electrode	Poor Mixture/Early Ignition	Check the fuel supply, advance angle
Oily	Black, dry, velvety.	CNG wear/Lots of oil	Measure the compression, check the proportion of the mixture

How to properly check the spark?

Twisted the candle, put a cap on it, and press the carving tightly against the "mass" (metal part of the engine). Pull the starter sharply. The spark should be bright blue and skip between the electrodes with a loud crackle. An orange or yellow spark is a sign of a weak coil or a discharged battery.

Mechanical problems and compression

If the fuel and spark are all right, you have to check the "health" of the engine itself. A compression drop is a sure sign of wear of the cylinder-piston group (CPG) or the osteoils. Low compression does not allow you to create the necessary pressure for effective combustion, and the engine simply does not pull.

Measure compression with a compressometer. For two-stroke motors, a value in the range of 9-12 atmospheres is normal (depending on the model); the spread of readings between cylinders more than 1 atmosphere indicates a problem; often worn piston rings or bullies on the cylinder mirror are to blame.

Another hidden reason is the air sucking through the crankshaft's coils, and the engine is poor, starts badly, and doesn't develop power, and you can check this by spraying WD-40 on the glands on the engine running: if the revs change, then the tightness is broken. exhaust: A clogged muffler or exhaust windows create backpressure that strangles the motor.

• 📉 Measure the compression in all cylinders.
• 🔊 Listen to the noises when you work.
• 💨 Check the glands for air suction.
• 🌫️ Make sure there is no smoke from the exhaust (except for the working mixture).

⚠️ Attention: Operating a low compression or air suction engine can cause the piston to overheat and jam in minutes.

Transmission and propeller

Sometimes the engine roars, the engine gains momentum, but the boat does not swim. This is a classic sign of slipping in the transmission. The gearbox could wear friction clutch discs (on the engines with a reverse gear) or turn the screw screw screws.

Check the state of the lower unit transmission. If after a long period of work the water in the gearbox has acquired an emulsion (coffee) color, then the leakiness of the ossels is disturbed. The water entering the gear oil leads to corrosion of the gears and jamming of the mechanism, which also slows down the course.

The wrong pitch is a common mistake. If you put a propeller in more than the recommended pitch for your boat and motor, the engine will not physically be able to spin it to operating speed. It will operate in an overload zone, slowly gaining speed and risking overheating.

Prevention and outcome recommendations

To prevent the problem of slow revs from catching you off guard on the water, you need regular prevention. Don't wait for the engine to start to malfunction. The scheduled maintenance includes replacing candles, checking fuel filters and visually inspecting the propeller before each season.

Use only high-quality oils and fresh fuels. AI-92 octane gasoline tends to oxidize and lose properties after 2-3 weeks of storage. Old fuel is the main enemy of the carburetor and the fuel system as a whole. When you preserve for the winter, be sure to drain the fuel or use stabilizers.

These simple rules will prolong your life. boat-engine And it's going to be very effective in all conditions, and remember that a timely diagnosis is cheaper than a major overhaul.

Frequently Asked Questions (FAQ)

Why does the engine only get halfway and stop?

It's probably a fuel filter or carburetor jellybox, it's not enough fuel to run under load, and it's also a fuel tank ventilation test, and if the valve is stuck in the lid, it creates a vacuum in the tank that cuts off the gas supply.

Can water in gasoline cause power loss?

Yes, water is heavier than gasoline and accumulates at the bottom of the tank, where the pump pump pumps it first. Once it gets into the cylinders, the water does not burn and disrupts the combustion process, causing interruptions and loss of traction. Be sure to use separators-sludges.

How often should I change the spark plugs on the outboard motor?

Candle life depends on oil quality and operating mode. On average, for two-stroke engines, candles are changed once a season or every 100 hours. For four-stroke engines, according to manufacturer's regulations (usually 200-300 hours). Always have a set of spare candles on board.

Does the water temperature affect the set of turns?

Indirect. In very cold water, the engine can warm up longer, and electronics (on modern motors) can limit the speed before entering the operating temperature mode. Also, cold water is denser, which slightly increases the load on the propeller, but this is rarely the main cause of power loss.