The reliability of water transport depends on the state of its power plant, and the heart of a two-stroke or four-stroke internal combustion engine is the heart of a water transport. carburetorIt is this unit that is responsible for creating a high-quality fuel-air mixture, on which the power, efficiency and stability of the engine on the water depend. In an aggressive aquatic environment, where humidity is increased and temperature regimes often change, the health of the fuel supply system becomes a critical factor for safety and comfort on fishing or cruising.
Many owners of outboard motors, whether powerful Yamaha compact TohatsuThey're facing launch problems or floating speeds, unaware that the root of the evil is pollution or misadjustment of that particular component. float-chamber and throttle Not only does it diagnose a malfunction, it also fixes it on its own without ever having to go to the service, but in this article, we'll take a look at the device, the typical breakdowns and the intricacies of carburetor maintenance, so that your motor always starts at half a turn.
It is worth noting that modern injection systems are gradually replacing classical solutions, but carburetors remain the standard for most outboard motors of small and medium power, their simplicity of design and maintainability make them indispensable far from civilization, where complex electronic repair is impossible. fuel-channel right-handed jelly These are the skills that every boat owner must master to confidently enter the water.
The principle of operation and Construction of the carburetor of the outboard motor
The fundamental principle of the carburetor is based on the Venturi effect: the air, passing through the tapering nozzle, accelerates, creating a zone of dilution, where the fuel is sucked from the float chamber. In outboard motors, this process has its own peculiarities, since the engine must operate stably at different angles of the boat's roll. Float mechanism Here plays the role of a valve that maintains a constant level of gasoline, which is critical when pumping.
The main elements of the node are diffuser, sprayer, needle And the giclero system is idle and main stroke, and when you open the throttle, the airflow increases, and more fuel starts coming through the atomizer. jellywhich are selected by the manufacturer for a specific model of the engine.
Why are diaphragm carburetors often in outboard motors?
Diaphragm carburetors (membrane) are less sensitive to the position of the engine. Unlike float carburetors, they can work even when the boat is heavily tilted or the engine is upside down (for example, during transportation or in emergency situations), since the fuel supply is due to the fluctuations of the membrane, not gravity.
It is important to understand the difference between idling and full load systems. At low speeds, fuel flows through a separate channel, bypassing the main spray, which ensures stable operation on the ground. idleWhen the throttle is opened, it comes into effect. booster, which injects an additional portion of gasoline, preventing power failure at the time of the start of the movement.
Stable operation of the motor at all modes depends on the synchronous operation of the idling system and the main sprayer; imbalance leads either to over-consumption of fuel or to overheating of the piston group.
Typical malfunctions and their symptoms
Diagnosing carburetor problems often begins with an analysis of the behavior of the motor, if the engine stalls immediately after warming up or does not hold single-turnThe problem is probably the sucking of unaccounted air or the contamination of the idling channel. The aqueous environment is insidious: condensate formed inside the tank inevitably enters the power supply system, causing corrosion of brass parts and oxidation of contacts.
Another common symptom is a "failure" when a sudden addition of gas is added, which indicates that the mixture becomes too poor in transition modes. carburettorIt's a motor that might have worn out or become dirty or become clogged with the main jet lag, and in such cases, the motor may stall under load or fail to develop full power, which is especially dangerous when trying to get on plane.
- 🔴 The motor stalls on idle - clogged channel XX or broken tightness of gaskets.
- 🔴 Black smoke from the exhaust is a re-enriched mixture that requires cleaning the air filter or adjusting the needle.
- 🔴 The engine "troit" or works unstable - water in the fuel or uneven supply of the mixture to the cylinders.
- 🔴 Increased fuel consumption – wear of the sprayer or improper setting blending.
⚠️ Attention: If you smell gasoline in the area of the engine when you're working, immediately turn off the engine. needle-valve does not hold pressure, and gasoline overflows over the edge, creating a fire-prone situation in the hold or under the casing.
Special attention should be paid to the condition of the sealing gaskets. Over time, rubber blubbers and cracks, allowing air to pass through. drain-manifoldIt makes it impossible to properly adjust the carburetor, and visually inspecting and replacing all rubber elements with each removal of the knot is a mandatory rule.
Diagnosis: How to identify the problem before removing the node
Before you grab the tools and start dismantling, you need to conduct an initial diagnosis to rule out other causes of unstable work. Often symptoms similar to a carburetor malfunction are caused by problems with the ignition system or fuel quality. spark-plateIf it is wet and black, the mixture is rich, if white and dry are poor, and the normal color is light brown.
Also worth checking is the fuel filter and the hoses. The cracks in the hoses can suck air, which the carburetor perceives as a command to deplete the mixture. Make sure that the fuel tank does not contain water that is heavier than gasoline and accumulates at the bottom, periodically getting into the tank. fuel-pump And then to the carburetor.
For accurate diagnosis, you can use a spray tester to find the air sucker. If you run a hot engine, spray the carburetor cleaner around the joints of the intake manifold and the base of the carburetor. If the engine speed changes (usually increases briefly), then this place is where it happens. air-suckerAnd the leakage is broken.
Use a transparent tank to drain a small amount of fuel from the carburettor drainage hole (if designed) or from the hose in front of it, allowing you to visually assess the presence of water or large debris without completely disassembling the unit.
Complete disassembly and cleaning of the carburetor
The maintenance process begins with the removal of the engine assembly, before that, be sure to close the fuel faucet and disconnect the battery. Carefully disconnect the throttle and suction cable, trying not to lose the springs and locks. gasket It is recommended to change it to a new one at each disassembly.
Disassembly should be done on a clean surface, laying out the parts in order of their removal. Pay special attention to the float: check its tightness by shaking it near the ear. If you hear splash inside, the float has lost its leakiness and must be replaced or soldered, otherwise the fuel level will be uncontrolled. All metal parts, except rubber seals and plastic, are chemically cleaned.
☑️ Checklist of proper carburetor washing
To clean the channels, you should use an ultrasonic bath or a specialized aerosol cleaner with a long spray tube, and you should blow the channels under pressure, making sure that air passes freely through everything. jellyDo not use metal brushes or wire to clean metal parts, as this can change the caliber of the holes and impair the accuracy of the fuel dosage.
⚠️ Attention: It is strictly forbidden to use acetone or aggressive solvents to clean the plastic and rubber components of the carburetor, as they can destroy the structure of the materials, which will lead to a rapid failure of the unit after assembly.
Adjustment and adjustment after assembly
Carburetor assembly is a process that requires care and accuracy. Install new gaskets with a thin layer of pure gasoline or special sealant for gaskets (if instructed). It is important to set the float height correctly using a rod or caliber, according to the specification for your motor model (for example, Mikuni or KeihinThis parameter determines the fuel level in the chamber.
After you put the carburetor on the engine and connect all the hoses, you start adjusting. Usually, there are two screws on the body: the screw. blending (usually located closer to the engine) and the propeller mixture Warm up the engine to operating temperature, which takes about 5-10 minutes of operation.
When you rotate the quality screw, find the position where the idling speeds are maximum. Then set the desired idling speeds (usually 900-1000 rpm for medium engines) with the number screw. Repeat the procedure several times to achieve perfect balance. The engine must respond to the opening of the throttle without delays or dips.
The correct adjustment of the carburetor is to find a balance between the stability of idling and the responsiveness of the engine to gas; too rich a mixture will wash the oil from the walls of the cylinder, and poor will cause overheating.
Table of main parameters and chiclera
Other engine models use different calibrations for jellyplates. Below is a reference table for popular carburetor models installed on outboard motors ranging from 2 to 15 hp. Remember that the data may vary depending on the year of production and engine modification.
| Motor model | Type of carburetor | Head jeckel | jicler xx | Position of the needle |
|---|---|---|---|---|
| Tohatsu 5bhp | Mikuni VM | #98 | #35 | 3rd duct |
| Yamaha 9.9bhp | Mikuni VM | #115 | #40 | 2nd duct |
| Suzuki 6bhp. | Mikuni BN | #100 | #38 | Average |
| Mercury 15 hp | Keihin | #120 | #42 | 4th duct |
| Parsun 2.6bhp | Chinese analogue | #72 | #28 | Average |
When replacing chicklers, it is important to consider operating conditions. If you use the motor in highlands or very hot climates, the mixture may require correction. However, for standard conditions of water bodies in Russia and the CIS, the factory settings are optimal. jelly-fish ensures the compliance of the throughput capacity with the declared specifications of the engine.
Frequent Questions and Answers (FAQ)
How often should I clean the carburetor on the outboard motor?
It is recommended to carry out preventive cleaning and inspection once a season, preferably before winter storage. If the engine is used intensively or fueled with fuel of questionable quality, check should be carried out every 50-100 hours.
Can I wash the carburetor without removing it from the engine?
Partly yes, using special fuel additives or aerosol cleaners fed directly into the intake manifold on the engine running can remove light deposits, but complete disassembly and mechanical cleaning are required to eliminate serious blockages and check the status of the float.
Why does the carburetor clog even when the gasoline is fresh?
The main reason is the oxidation of fuel components during prolonged contact with air, especially in the float chamber, where gasoline can remain after the engine stops, and condensate from the air or rust from the old fuel tank can enter the system, forming an abrasive mixture that clogs thin channels.
What gasoline is best used for carburetor outboard motors?
The best choice is AI-95 gasoline with an octane number recommended by the manufacturer (usually 92-95). It is important to ensure that the fuel is alcohol-free (ethanol can destroy rubber seals of old carburetors) and was fresh. It is not recommended to store gasoline in the tank for more than 3 months.