Primer Bulb

C

cmcstotts

Cadet
Joined
Aug 12, 2011
Messages
8
I have a dumb question. I was running my engine the other day and the primer bulb was sucked flat. Does this indicate that the vent on the gas cap is not working? Can someone explain to me the operation of the primer bulb and the vent cat?
 
Barnacle_Bill

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: Primer Bulb

The tank must be vented. As fuel is drawn out the vent allows air in to takes its place. With the vent closed the primer bulb will collapse and the motor will stop running.
 
79Merc80

79Merc80

Senior Chief Petty Officer
Joined
Nov 22, 2007
Messages
673
Re: Primer Bulb

Posting the make, Model, HP rating, and seril # would help others with the information.
 
j_martin

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Primer Bulb

The primer bulb is simply a squeeze bulb with 2 check valves in it. It operates as a hand pump. When the engine is running, fuel is pulled through the bulb and 2 check valves. If something is plugged up between the primer bulb and the tank vent, it will be sucked flat. It's just like when a piece of strawberry gets stuck in the end of the straw when you're enjoying a milk shake.

hope it helps

John
 
C

cmcstotts

Cadet
Joined
Aug 12, 2011
Messages
8
Re: Primer Bulb

I have a 1995 15 hp mercury, s/n: 0g153580.
I had mutiple problems. I bought a new 3 gallon gas tank and hose/primer bulb from bass pro. The vent on the new tank was no venting corretly. I corrected that problem and noticed the bulb would not firm up. I removed the connector and fuel pick up cap. The fuel pick up pipe was not conntected securely to the pick up cap. Swapped the pick up pipe around so it fit securely to the pick up cap. I ran the boat for 15 minutes no problem.
Thanks for all of the repsonses.
 
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