Diaphram carburetor primer pump bulbs

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  #1  
Old 07-26-09, 11:40 AM
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Diaphram carburetor primer pump bulbs

Why is it that some primer bulbs are very easy to push while some are very hard to push? The reason I ask, is that I replaced a RBK65A Zama carburetor on a PB230LN Echo blower and it's hard to push. Although, with this new carburetor the blower now works fine.
 
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Old 07-26-09, 02:11 PM
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I think it has to do with the check valves in the primer base assembly and whether it is working properly, when you push on the primer it should return fuel to the tank and suck new fuel through the carb from the tank, if the outbound valve is varnished, dirty or sticking the fuel doesn't want to go out. If the same is happening on the input side the bulb will stick down and take a long time to fill, also some of the primers are softer than others. Kinda like that. Have a good one. Geo
 
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Old 07-27-09, 04:38 AM
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Thanks for the reply Geo. That's about what I was thinking. I've got a Husqvarna string trimmer and it's very easy to prime.
 
  #4  
Old 07-29-09, 09:57 AM
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I sent an E-mail to Zama concerning this same question and here is their reply:

"The hard primer bulb can be related to a couple of different things. As long
as the unit is operating normally, then it is more of a nuisance than
anything else. The main reasons are stiff check valve springs, slightly
thicker bulb material, and high gas tank pressure. The primer may get easier
to push as the fuel level in the tank drops. You can also double check this
cause by opening the gas cap and priming the carb. As I said before, as long
as everything is working properly I would just ignore it. We have received
brand new carburetors here that have the same symptoms but run perfectly
fine. Hope this helps!"
 
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Old 07-29-09, 04:16 PM
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I guess I was "kinda/sorta" close to why. Have a good one. Geo
 
  #6  
Old 07-30-09, 07:40 AM
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Since all but one piece of my equipment predates primer bulbs, I haven't had to mess with them until this summer. Thanks guys for the education on what to look for in my old trim mower.
 
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