Why the outboard motor is not started on the cold: diagnosis and repair

The situation when the outboard motor is not started on a cold one is familiar to many owners of water equipment, regardless of whether you have a powerful engine. Yamaha It's the Chinese equivalent of a budget, and it comes at the most inopportune moment: early morning fishing, when the air is cool and the fuel is not warm enough in the tank, and instead of a confident start, you hear only rare sneezes or brief flashes, after which the engine will stop again.

The problem with cold start is that the fuel-air mixture needed to ignite is disturbed, and unlike a hot engine, where the fuel evaporates instantly, the cold metal of the cylinders and intake manifold condenses the gasoline, preventing it from becoming a flammable fog. launcher It requires a special approach and often mechanical intervention or adjustment.

In this article, we will discuss the main reasons why boat-engine We'll touch both two-stroke and four-stroke units, look at the nuances of carburetors and injection systems, and give clear instructions for troubleshooting yourself.

Physics of the process: why the cold engine is capricious

To understand how to fix a problem, you first need to understand what is going on inside. combustion engine The main enemy here is condensation. When you pull the trigger on the starter, the piston sucks in air mixed with fuel. If the engine is cold, the cylinder walls act like a refrigerator, turning liquid droplets of gasoline back into liquid settling on the walls instead of burning.

For successful ignition, the mixture must be significantly richer than at operating temperature. carburetor Or the electronic control unit (ECU) has to supply more fuel and less air, and if it doesn't, the spark simply can't set too poor a mixture on fire, which is why manufacturers have designed special enrichment mechanisms.

And then the viscosity of the oil increases dramatically at low temperatures, and that creates additional resistance to the rotation of the crankshaft, and it's harder for the starter to spin the engine to the required rpm, which is enough to suck in the fuel, and then we end up with a vicious circle: low rpm, poor mixing, no starting.

⚠️ Warning: Attempting to start a candlelit engine by long torsion with a starter will only make the situation worse. You risk draining the battery to zero and completely flooding it. spark-plugThen the spark will become impossible.

It's important to consider the quality of the fuel. Old gasoline, which has been in the tank all winter, loses its volatile fractions. Light components evaporate first, leaving heavy, which burn poorly. boat-engine It will be very difficult to start even after careful adjustment.

Ignition system: candles, coils and electrician

The first thing to check if the engine doesn't start is if there's a spark, and on a cold engine, the spark discharge is as high as possible, and a weak spark that can still set the mixture on fire in a hot cylinder, on a cold one, it just dies in a vapor-rich environment. spark-plug.

Turn the candle out and examine its electrode. If it's black, wet with gasoline or covered with soot, the spark will go on the surface of the insulator or not at all. The gap between the electrodes also plays a critical role: too much gap is harder to break, especially when the compression has not yet reached its peak due to the slow speed of the starter. NGKSpecifically designed for your engine model.

And high-voltage wires, too. In the humidity of the water, micro-cracks in the insulation can leak current. In cold, when the air is denser, the breakdown can be easier. Check the candle cap: it should sit tight, without backlashes, and inside should not be oxides.

• 🔌 Visual examination: Check the integrity of the wire insulation and the absence of breakage marks (blue sparks) in the dark.
• ⚡ Clearance measurement: Use a probe to check the gap of the candle, it must meet the manufacturer's specification (usually 0.7-0.9 mm).
• 🧹 Clearing contacts: Clean the battery terminals and the mass connection, the oxides reduce the starter's starting current.

If there is a spark, but it is weak (thin, reddish), the problem may lie in the ignition coil or battery charging. A cold lead-acid battery gives off less current than a warm one. If the voltage at the terminals when you try to start falls below 9.5-10 volts, the starter will spin sluggishly, and the spark will become unstable.

Fuel system: carburetor, gas pump and filters

The most common reason why boat-engine It's not cool, it's in the fuel system, and it's evaporating, leaving tar deposits behind, and in the summer or in the long run, these deposits are clogged by carburetor chicks, especially those that are responsible for triggering.

In carburetor engines, the cool start is caused by a pump system (enricher) that overlaps part of the air channel, creating a strong dilution and tightening more fuel. If this mechanism is jammed or the suction cable is stretched, the necessary enrichment will not occur.EFI) the temperature sensor is responsible for this, which may give incorrect data if it is defective.

And you also have to look at the back valves in the fuel hoses and the pump pear, and if the valve doesn't hold, the fuel drains back into the tank, and it takes the pump time to fill the carburetor again, and it's a waste of time to swing the pears for a long time.

Element of the system	Symptom of malfunction	Elimination method
idle-clothing	The engine will stop immediately after launch	Carburettor wash, jellyclear cleansing
Fuel filter	Weak pressure, engine is pressurized	Replacement of the sludge filter
Enricher (suction)	It is impossible to start without a hand sucker.	Adjustment of the cable or replacement of the electric valve
Benzonesus	Lack of fuel supply to carburetor	Repairing the membrane or replacing the pump

Pay special attention to the quality of the gasoline in the tank. If you left the equipment for the winter with a full tank without a stabilizer, the gasoline could dissipate. The water that entered the system will settle at the bottom of the float chamber of the carburetor, completely shutting off the fuel supply. flushing.

Compression and mechanical state of the engine

Low compression is a scourge of old two-stroke engines, but four-strokes are not immune to this problem. To ignite the mixture, you need a certain pressure at the end of the compression stroke. If the rings are worn out and the cylinders have bullies, the pressure drops, the temperature of the mixture does not reach the desired values, and there is no flash.

In two-stroke engines, crankshaft coils play a critical role. If they dry out in the cold or just wear out, the engine starts sucking air through the crankcase. This disrupts the process of purging and filling the cylinder with fresh mixture. The engine can run at high revs, but at cold and low revs it will stall.

Compression testing with a compressometer is a mandatory procedure when looking for the reasons for a bad start. Normal values for two-strokes usually start from 8-9 atmospheres, for four-strokes - from 10-11 atmospheres and above, the range of readings between cylinders should also not exceed 1 atmosphere.

⚠️ Warning: If compression is absent or critically low, prolonged launch attempts may result in a hydraulic shock (if water hits the cylinder) or the destruction of the shaking-piston group.

Another mechanical factor is the thermal gaps of the valves (for four-stroke motors). If the gaps are lost, the valves may not close tightly, which leads to loss of compression. Valve adjustment often solves the problem of unstable starting and idling.

Specifics of launching two-stroke and four-stroke engines

Launch approaches two-stroke and four-stroke Two-stroke engines are more sensitive to the quality of the mixture and the condition of the coils, and they are characterized by the procedure of pumping the cylinders before starting: several times pull the starter with an open throttle (without a spark) to blow the cylinder from excess fuel if there is a pumping.

Four-stroke motors, such as Honda or SuzukiThey have an oil crankcase. The cold oil is thick, and hydraulic compensators (if any) or lubrication systems take time to go into operation. Often these motors require longer starter work to create enough intake manifold.

It's important to use the suction lever correctly. On carburetor motors, the algorithm is usually this: close the suction -> 1-2 jerk with the starter -> open the suction half -> start -> warm up -> full opening. Violation of this sequence leads to either flooded candles or no start.

The secret of a "hot" launch after a failed cold

If you pour gasoline on the candles and the engine stops grasping, twist the candles, blow the cylinders with a starter (with an open throttle), wipe the candles dry and burn them with fire (caution!). Roll back in and try to start without a suction with fully open gas.

The fuel pump is important for injection systems, and when it starts to ignite, it has to hum for a couple of seconds, creating pressure in the ramp, and if it doesn't, the ECU won't give the command to start because it won't see the right pressure in the fuel line.

Seasonal maintenance and prevention

So the question, "Why does the outboard motor start badly on the cold one" doesn't get up every morning, you need to be properly preserved. The main mistake is to leave the gasoline in the system for the winter. The fuel oxidizes, forms resins that clog the channels dead, and before storing, you need to make fuel from a carburetor or use a special stabilizer.

Keep the engine dry. The extreme temperature changes create condensation inside the crankcase and the tank. If you can't, cover the machine with a breathable cover to avoid direct moisture but leave ventilation.

Regularly changing fuel filters is a cheap way to avoid big problems. The water in the tank is the main enemy. Use special water separators and periodically check their contents. Also remember to change the oil in the gearbox and engine (for 4T) according to the regulations, since the spent oil contains acidic compounds that destroy metal.

• 🛢️ Conservation: Be sure to spray the canning oil into the cylinders before long-term storage.
• ⛽ Stabilizer: Add the additive to the tank before the last outing of the season.
• 🔋 Battery: Remove the battery for the winter and keep warm, periodically recharge.

Frequently Asked Questions (FAQ)

Can I use AI-95 gasoline instead of AI-92 for outboard motor?

Using gasoline with a higher octane number than recommended by the manufacturer can lead to overheating of the engine and difficult start on cold, as it burns at higher temperatures. Tohatsu, Yamaha Or another brand.

Why does the engine start and immediately stop if you do not hold the gas?

Most likely, contaminated idle channel in the carburetor or incorrectly configured screw quality mixture, and it is possible to suck unaccounted air through the gasket of the intake manifold.

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

The recommended interval is once a season or every 100 hours, but if you notice that the engine is starting to start worse on the cold, you should check the candles earlier.

Does the water in the tank affect the cold start?

Yes, water is heavier than gasoline and accumulates down there, and when it starts, it hits the carburetor first, blocking the fuel supply, and the motor can grab the remaining gasoline in the float chamber and immediately stall.

Do I need to heat the carburetor with a hair dryer in winter?

In extremely cold weather (below -15°C), a light warm-up of the intake manifold can make it easier to start by vaporizing the fuel, but it must be done carefully so as not to damage the plastic parts.

Compliance with these guidelines and regular maintenance will allow your outboard motor to serve faithfully for many years, delighting with a confident start in all weather.