Marine Engine Faults


In particular, the issue of outboard marine engine malfunctions of boats used for tourism purposes is one of the most feared issues for boat and yacht owners or operators. For this reason, we will try to address the solutions of the most needed problems such as boat malfunctions, how to fix yacht engine malfunctions.

Engine Does Not Start Does Not Start

Different things may be causing the Marine Engine Not Starting or Not Starting. If we evaluate it in two different conditions, it may be that the starter does not start, that is, it does not receive the starter, the starter works, it turns, but the engine does not work. Let’s evaluate these two main reasons in a cause-effect relationship.

Starter Not Working (Not Starting)

  • A physical problem may have occurred in the starter or starter relay. If a jam has occurred in the gear we call the Bendix Gear, the starter may not be working or turning. You need to make sure of this by providing the necessary controls.
  • Spark plug cables, which are the most important element of ignition, may be reversed. In this case, the engine will not start because there will be no effective ignition.
  • Cracking and contamination in spark plugs, which are the ignition elements, can also cause the ignition to skip. This prevents the voltage required for the engine to run down to the cylinder. If the spark plug ceramic is cracked, that spark plug will not do you any good. It needs to be replaced. Even if ignition is not made due to pollution, this time cleaning with contact sprays or fine sandpaper is required.
  • A looseness in the battery cable connections also prevents ignition and starting. Check the battery connection cables and tighten them if there are any loose connections.

Starter Runs But Engine Doesn’t Run

  • If the engine does not rotate even though the ignition mechanism works, it is necessary to check whether the fuel is coming to the cylinders. If you have run out of fuel, you are likely to experience this problem. If you run out of fuel, top up and try again.
  • Outboard marine engine malfunctions can occur if there is an incorrect connection in the fuel hose even though there is fuel in the tank. Check the fuel hoses. If there is an incorrect connection, go to the correct way.
  • If you have added new fuel to the tank, air may have formed in the fuel hose. In this case, remove the fuel hose from the engine inlet. Press the starter 5-6 times. When you see fuel coming from the hose, reconnect the hose to the engine and try to start it.
  • If you get the fault that the marine engine does not start even though the fuel reaches the engine, there may be a contamination in the fuel hose or fuel filter. In this case, if you replace the hose and filter, you will eliminate the pollution factor.
  • As a safety precaution, the engine may not start if the throttle is left in the forward or astern command. You can try to start it again by moving the throttle to the idle (IDLE) position.
  • One of the possible problems encountered in this type of outboard marine engine failures is due to the wrong fuel-air mixture ratio of the carburetor. In an unsuitable air mixture, what we call engine choking can occur. Make sure a proper carburetor adjustment is made.
  • The marine engine lubrication system works a little differently. The fuels of such engines are generally mixed with 1/50 oil. As a result of unsuitable oil-fuel mixtures, it has been observed that the engine starts but does not operate. Make sure that there is sufficient oil mixture in the fuel.
  • Mussels, crustaceans and insects may occur in marine engine propellers that are not operated for a long time. This situation can cause the engine to be forced first and eventually not start. If there is such a situation, the impeller should be cleaned and tried again.

Engine Runs But Loss of Power and Low Performance

  • In such a case, the first thing to suspect should be the quality of the fuel. If there is water in the fuel, power losses and performance degradation may be observed because there will not be a smooth and sufficient ignition. In this case, water must be taken from the fuel tank. If this cannot be achieved, the fuel must be changed completely.
  • This problem can also be seen as a result of not regular firing. Care should be taken that the spark plugs are not cracked and dirty.
  • As a marine engine ignition system failure, the ignition coil and capacitor issue also causes ineffective ignition and loss of performance. If there is a problem with the ignition system elements, they must be replaced.
  • A damaged situation in the propellers also causes inefficiency in the conversion of the power produced by the engine into energy. Therefore, if there is a bending-like deformation on the propeller blades, power and performance testing should be done by correcting the propeller blades.
  • Shellfish on the propeller can also cause a performance drop in the power produced by the engine. This problem can be fixed by cleaning the propeller.
  • Bending the engine tail, which we can also call the marine engine shaft path, can cause the propeller to not work properly and efficiently. This can also result in shaft shear. When a problem is detected in this way, you should fix the engine queue.

Engine Sticks During Running

  • The carburetor needle valve setting that mixes the fuel-air may be out of order. Make the appropriate adjustments.
  • Again, if sufficient air-fuel mixture cannot be provided in the carburetor, a marine engine misfire may occur. Try again with the appropriate carburetor adjustment.
  • If the fuel filter is clogged, the engine will not receive fuel regularly. When the fuel is low, the engine may jam and misfire. Clean the cleaned fuel filters. Otherwise, you need to replace the filter with a new one.
  • The distributor cap may have cracked. Due to the crack, the engine cannot achieve the proper efficiency and starts to misfire. The only solution is to change.
  • Improper coolant temperature may also cause the marine engine to stall during operation. Check the coolant inlets. If there is a blockage, clean it.
  • The coolant pump may not be sending enough water to the engine. Test the pump. There may be wear on the wings. Refresh and deploy.

Engine Blowing Blue Smoke

Blue smoke is the main cause of oil burning in internal combustion engines. It is even a classic question type in driving license exams on land. If such a problem is encountered with regard to outboard marine engine malfunctions, the following situations should be suspected and precautions should be taken accordingly;

  • The spark plugs may be coated with oil. Remove and clean the spark plugs.
  • This can happen if the amount of oil added to the fuel tank is too high. If gasoline is added and the oil rate is reduced, this problem will go away. Working with excess oil will also cause the spark plugs to become dirty in a short time.

Engine Speed ​​Not Constant

  • If the marine engine is not properly attached to the propeller, the propeller is going in and out of the water. When it enters the water, the propeller, which encounters resistance, is forced and its speed decreases. When you come out of the water again, the number of revolutions increases as the resistance disappears.
  • There may be a problem with the carburetor setting that does not mix the fuel-air properly. Check the boat engine carburetor setting. If it is defective, make appropriate adjustments.
  • If you are not using a propeller suitable for a marine engine, the power produced by your engine may be preventing the propeller from working efficiently. If the engine speed is not constant despite using the right propeller, it is necessary to check whether there is any deformation in the propeller. If there is deformation, the problem must be corrected.

Outboard marine engine failures are generally like this. Some items look the same, but it is a fact that the same malfunction causes different problems. I wish you trouble-free days.

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