Boat fuel line bulb or primer bulb won't get hard - Troubleshoot your engine
Our viewership consists of about 80% males above the age of 55, so let's steer away from the blue pill jokes about fixing something that won't get hard and get to right down to it.
The primer bulb is located on the fuel line between the gas tank and the outboard (or inboard) engine. When you “prime the carburetor”, you are pushing fuel from the carb bowl to the barrel (using the bulb). Once there is gas in the barrel, it will easily be sucked into the cylinder of the engine. Therefore making starting the engine easier when it is called.
Top questions about bulbs not getting hard
What is the purpose of a primer bulb?
The primer bulb is here to manually fill the carburetor barrel with gasoline when you want to start your engine cold. After you press it, a vacuum is created and gas will be drawn into the intake fuel line all the way to the carburetor. A one way valve present inside the bulb prevents gas from going back down the hose.
Where is the primer bulb?
The fuel line bulb is located between your gas tank and your engine. If you have a fuel filter (water separator), it will most likely be located between the filter and the engine, in other words, down-flow from the filter.
Is the primer bulb supposed to stay hard?
Yes. Because the part of your engine from the tank to the carburetor is an air-tight system, it should get hard when you pump and stay hard for at least an hour. If it does not stay hard when primed, it means you have a leak, check the test above to find where it is.
How do I know if my primer bulb is bad?
If you think your primer bulb might be bad it is probably because you cannot prime your engine (send fuel to the carburetor when starting cold). This issue can have multiple causes. It could be an issue with the gas tank, the fuel line, the engine, or the bulb. To know if the issue comes from the bulb, check this article’s tests, specifically number 2, 4, 5, and 7.
I have to pump a primer bulb to keep the outboard running, why is that?
This might be because your carb bowl is not filling up as fast as you are consuming fuel, and you need to pump the primer bowl to keep the engine running. This could be because the tank is not sending gas fast enough. Check the pickup tube, fuel line, bulb, and water separator if any of them is clogged. If that’s not it, you might have an engine issue.
Outboard primer bulb goes soft, why is that?
Once primed, your bulb will slowly start to go soft once your engine is running. It is the case because the pressure that has built up between the bulb and the carburetor (thanks to pumping the bulb) will start to decrease as fuel is being consumed by your engine. If you bulb goes soft as soon as you stop priming, then you might have a leak and you should check the tests in this article.