primer bulb

[B.D]

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What purpose does the primer bulb serve other thatn filling the carbs, Also if the bulb stayes soft while running does this indcate you need a new bulb or somethingelse?

 

[diaric]

Re: primer bulb

fills fuel pump and carbs. has check valve so fuel only goes one way. should pump up hard, or pump or carbs have an issue. goes soft while running

 

[B.D]

Re: primer bulb

so if the bulb goes soft it is bad?

 

[diaric]

Re: primer bulb

if your pumping up before you start and it goes soft, fuel is leaking in motor or out of bulb. when running, going softer is normal

 

[Silvertip]

Re: primer bulb

If your engine has a primer system instead of a butterfly choke system, it is essential that the primer bulb pump up firm. If it does not, the primer system won't work and cold starts will be difficult. Remember, once the engine starts, fuel is being "drawn" through the fuel line and primer bulb so it will become soft. If it is ever sucked flat however, that says there is a fuel restriction between the bulb and the pickup tube in the tank.

 

[Boatleech]

Re: primer bulb

I've got a 1994 or 1995 Mercury 40HP 2-stroke with the soft primer bulb problem. It's a new bulb and fuel line. Seems to run OK, but the soft bulb bothers me.

I've rebuilt the fuel pump, so I only see 2 other places the fuel could be going: through the oil-line check valve to the oil pump, or through the carburetor(s).

Plan now is to just clamp off interconnecting fuel & oil lines to determine where the leak occurs. If it's the carburetor(s), where do I go from there?