air leak in fuel line symptoms outboard

Air Leak in Fuel Line Symptoms Outboard: Elaborately


It is not uncommon for an outboard owner to face an air leak in the fuel line. It is sounding simple right? But it may lead your outboard to some major issues like engine failure.

So, what are the air leak in fuel line symptoms outboard? 

Well, there are a few symptoms that indicate air leaks in the fuel line. Dying of engine, softer fuel pipe, firing, fuel line bubble, and discontinuity of power in the carburator are some of the significant symptoms. Also, these symptoms might cause your outboard some other issues as well. 

However, if you got some time to spend knowing the topic in detail, we are here to enlighten you. Here is an entire article the following about the stated issue. 

So let’s jump right into it. 

Air Leak in Fuel Line Symptoms in Outboard Engine

Sometimes the air leak in the fuel line can be a major issue for your outboard. So you must know the symptoms beforehand. Here are all possible symptoms discussed in the following segment.

Softer Fuel Pipe

The airflow keeps the pressure of the fule line stable. Since the air gets stuck in the fuel line, the total pressure decreases. Hence, the fuel pipe seems loose and softer. 

Dying of Engine

Engine dying is the major drawback of air leaks in the fuel line. Low power in the engine is the symptom to detect the dying of the engine. 

The engine will go rough at the beginning. And gradually it will lose its RPMs. As the air is getting stuck day by day. The engine will also function it down.

Prime in Fuel Line

You might detect prime in the fuel line sometimes. Which also indicates a leak in the fuel line of your outboard. You might be wondering where the primer bulb is located. 

Let me tell you. It is between the gas tank and the engine. The purpose of this is to fill the carburetor with fuel. 

When you fill the fuel tank, the engine should be switched off. You need to turn on the ignition switch. Don’t forget to turn the stop switch to run and continue until put gets stopped. Also, turn the switch off. 

Lean Situation

It is not always specific for the air leak to take place at a particular place. There are a few specific places for this to occur. One of those places is between the fuel pump and the tank.

When this occurs, the air gets stuck but not the gas into the tank. For this reason, the right amount of fuel cannot get pumped. And the whole situation is called the ‘lean situation’. 

Power Fluctuation in Curborator

It is easier for the fuel to get sucked inside the fuel line than the air to get lifted. And this situation leads to the carburetor having a scarcity of fuel. 


In some cases, firing can take place due to an air leak in the fuel line. Leaks that are found between the fuel pump and carburetor can create a fire. This is not the end. 

Sometimes, it can cause system disorder at times. 

Bubble in Fuel Line

While changing the fuel line, there will be visible bubbles on the suction side.

Air Leak in Fuel Line: 5 Necessary Steps After Detection

As we already know, the leakage may occur in several places. Initially, it is hard to tell the exact place of leakage. Here are a few steps to detect your fuel line leak in the following.

Step 1: 

After figuring out there is a leakage problem, the first step is to suck out enough fuel. This way the leak will come out. 

The trick is to keep the engine running for 10-20 minutes at a stretch. You can check after that if the engine is running smoothly for long or not. If there is no ejection for around 30 minutes, then the engine is running fine. 

Step 2:

You can check on the carburetor connection and rebuild it if needed. You can establish new fuel lines and connections and pumps to the engine. This sometimes helps to get rid of invisible air leaks. 

Step 3:

Check every connection individually. Also, try to identify damages of any parts. If needed then replace the damaged parts. 

Step 4:

It is very important to check on every single part of your outboard. Check the plugs, tubes, and nozzles. Don’t miss any delicate parts of the system. 

If you find any corrosion, that might be the reason for air in the fuel line. So, try to get rid of the damaged parts as soon as possible and rebuild if needed. 

If you could detect and solve the leak problem, tie a nylon strap around the fuel line.

Step 5: 

Check the Throttle, pistons, and choke linkage if they are working properly. If you still couldn’t get rid of the issue get it checked with a professional. If possible, get the entire system checked. 

Are you still worried about the whole situation? If so, just calm down. There are a few products that would help you to cope with the whole situation. 

Let me recommend some of those.

Product Name Product Details Product Picture
Attwood Johnson/Evinrude/OMC Fuel Hose Fitting

This is used on both ends of the fuel line. It will connect the tank fitting and motor.
Attwood 93038AI7 Primer Bulb for 3.8 inch ID Fuel Line 

The primer bulb is located between the gas tank and engine. It is used to fill the carburetor with fuel while the engine is getting cold.
Pactrade Marine Fuel Line Assembly Mercury 3/8″ Hose Barbs Primer Bulb Connector The marine fuel line hose barb is a connector of your primer bulb. 

 In case of any customization in your system, the suggested products above would help you through.  


What are the drawbacks of air being in the fuel line?

There are a few drawbacks of air being in the fuel line. For example, a discontinuity in starting, stalling, or dying of the engine. So, if you detect air in the fuel line, try to get rid of it as soon as possible. To keep your fuel line Airfree, clear the hose into the fuel line. Next prime the engine up and start it all over again.  

How expensive it is to replace the fuel line?

Replacing the fuel line of an outboard motor is quite expensive. Sometimes you cannot but replace the fuel line of the outboard motor. However, if you want to do so, the cost is anywhere around $120 to $500. The cost mostly depends on the model and the making.  

Why does the outboard motor die at full throttle?

An engine can die at a full-throttle due to a clogged air filter. A clogged air filter also causes your engine to die and idle at times. So monthly maintenance is a vital part of your outboard motor and make necessary replacements while needed. 

Final Word

That was everything we could enlighten you with about air leak in fuel line symptoms outboard. Hopefully, we could help you to understand the whole issue and solutions to the problems accordingly. 

One added tip, you have to make sure your outboard fuel line is getting its monthly maintenance. It would avoid such issues to happen in the future. 

Finally, have a great day!

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