Avoiding Boat Engine Issues: Managing Old Gas

Old gas can cause a lot of problems for a boat engine. The older the gas, the worse it is for the engine's performance, and it can lead to issues such as sputtering, clogged injectors, and engine knocking. Bad gas can also be identified by its appearance and smell—it is darker, has a sour smell, and forms water inside the fuel tank. This is known as phase separation and can cause hard starting and rough running. Additionally, old gas can damage the engine severely, leading to inefficient engine performance and higher gas consumption. It is recommended to use a fuel stabilizer to increase the storage time of the gasoline and prevent issues caused by old gas.

Boat engine failure

Old gas in a boat can cause the engine to fail. Bad gasoline is the most common cause of boat engine failure. This can happen when boats are stored away for the winter with old fuel still in their tanks. Gasoline that is a couple of months old is generally okay, but if you're storing your boat for longer than that, you may run into problems.

Symptoms of Old Gas

Old gas can be identified by its appearance, smell, and the way the boat runs. Old gas often has a darker colour and a sour smell. When trying to start the boat engine, it may be tough to start, and it'll run rough when it does. You may also notice rough idling, sputtering, and stalling.

Effects of Old Gas on Engine

The effects of using old gas in a boat engine include:

• Engine may not start
• Reduced acceleration
• Engine puts out steam
• Engine knocking
• Clogged injectors
• Clogged fuel filters
• Poor engine performance
• Higher rate of gas consumption
• Engine misfires
• Engine damage

Preventing Engine Failure

To prevent boat engine failure due to old gas, it is important to either use the boat frequently enough to burn through the gasoline or take measures to ensure the fuel does not go bad. This includes using fuel stabilizers, keeping the fuel tank more than half-full during winter to reduce condensation, and storing the boat in a warmer environment.

Engine knocking

The fuel-air mixture in an internal combustion engine is meant to be ignited by the spark plug at a precise point in the piston's stroke. However, in the case of engine knocking, the peak of the combustion process occurs prematurely, resulting in a shock wave and increased cylinder pressure. The effects of engine knocking can range from negligible to completely destructive, with severe cases leading to catastrophic engine failure.

In the context of old gas affecting a boat engine, engine knocking can be a symptom of using outdated fuel. Old gas tends to lose its combustibility due to evaporation and oxidation, leading to suboptimal engine performance. While it is generally safe to use old gas mixed with fresh fuel, it is important to consider the age and condition of the old gas. Gasoline that is more than two years old is not recommended for use in boat engines due to the risk of engine damage.

To prevent engine knocking caused by old gas, it is advisable to use fresh, high-octane fuel and ensure proper maintenance of the engine's fuel system, including the fuel pump, injectors, and filters. Additionally, regular engine maintenance, such as keeping the engine clean and well-lubricated, can help mitigate the effects of engine knocking.

Clogged injectors

Clogged fuel injectors are a serious issue that can be caused by old gas in a boat. Fuel injectors are vital to the lifecycle of an engine, and clogged injectors can lead to significant engine problems.

Fuel injectors become clogged when old gas dries and turns into varnish, or when debris and sediment from storage tanks make their way into the injectors. This can cause the engine to run very rough, cylinders to misfire, and the engine to struggle to start or not start at all. Bad fuel consumption and reduced engine power are also symptoms of clogged injectors.

Diagnosing clogged fuel injectors can be difficult as the symptoms are similar to those of a bad coil, dead spark plug, or electrical problem. However, there are some tests that can be performed to check for clogged injectors. One method involves starting the engine when cold, letting it run at idle for 5-10 seconds, and then checking the exhaust manifolds. If one of them is not warm, this could indicate a clogged injector. Further tests include inspecting the injector connector for corrosion and using an ohm meter or Noid light to check for power to the injector.

To prevent clogged injectors, it is important to keep fuel injectors clean and maintain the fuel system. Using fuel additives or stabilizers can help prevent condensation and debris buildup. It is also recommended to double or triple the dosage of stabilizers before any storage longer than a month. Additionally, avoiding ethanol blends can help, as they attract moisture and can cause corrosion in hoses, filters, O-rings, and fuel pumps.

If fuel injectors are already clogged, the best course of action is to remove them and send them to a professional for cleaning and servicing. While some home-cleaning methods are available, they may not thoroughly clean the injectors, and improper cleaning could lead to engine damage. Professional fuel injector servicing typically includes cleaning, calibration, and repair, and it should be done every 300 engine-run hours or every three to four years.

Poor acceleration

Old gas can directly affect acceleration due to its reduced combustibility. Over time, the volatile compounds in gas that allow it to burn begin to evaporate, leading to a gummy varnish-like substance forming. This results in a loss of combustibility and, consequently, poor acceleration.

Additionally, old gas can cause engine problems such as knocking, sputtering, and clogged injectors. These issues can further contribute to poor acceleration. It is essential to address these problems promptly, as severe or permanent engine damage may occur if left unchecked.

To prevent poor acceleration due to old gas, it is recommended to use a fuel stabilizer or conditioner. This can help maintain gas quality and improve combustibility. However, if the gas is extremely old (over two years), it is best to remove it entirely and refill the tank with fresh gas.

Engine sputtering

Old gas can cause engine sputtering due to the formation of gum and varnish-like substances in the fuel system. This can disrupt the flow of fuel to the engine, resulting in incomplete combustion and sputtering. Water contamination in the fuel can also lead to engine sputtering. Over time, ethanol-based fuel can absorb water, leading to phase separation, where water settles at the bottom of the fuel tank. This can interrupt the flow of fuel to the engine, causing sputtering and other issues.

To prevent engine sputtering due to old gas, it is essential to maintain fresh fuel in the tank. If you plan to store your boat for an extended period, consider using a fuel stabilizer to slow down the oxidation process and prevent water buildup. Additionally, keeping your tank more than half-full during winter can help reduce fuel contraction and condensation, minimizing the chances of engine sputtering.

If you suspect that your boat engine is sputtering due to old gas, it is recommended to drain the old fuel and refill the tank with fresh gasoline. You can also mix old gas with fresh fuel, but this may still result in some sputtering. In some cases, you may need to clean or replace fuel filters and hoses to ensure a smooth fuel flow to the engine.

Frequently asked questions