FS90 faulty primer bulb

Gahzula said:

Hi everyone,

Just wondering if anyone would happen to know why my primer bulb doesn't pickup any fuel. I have had the carb apart when I bought the machine second hand and cleaned it up nicely. (didn't prime before this clean up) When fully pressed it comes right back up almost instantly with no fuel at all. Here is a video of the primer bulb once I've had the strimmer running for around 10mins:https://youtu.be/YS8v3eip5xsIf anyone could advise then it would be greatly appreciated!Many thanks Jay

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deminin said:

Have you tried a new Primer Bulb? This one looks kind of "brown", and may not be providing the vacuum needed to prime the carb. I keep a few bulbs on hand....just a few cents on EBAY....and replace them routinely whenever the bulb starts to loose its "elasticity", and starts to turn color.

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bertsmobile1 said:

The PURGE bulb draws air , then fuel out of the carb and returns it to the fuel tank, which is pressurised to around 7 psi.
In order to do this it has a check valve ( some times 2 ) so the air & fuel can only go one way, from the carb to the tank.

If yours is blowing bubbles then chances are the check valve is not working and air is being pushed back from the tank through the purge bulb and then most likely through the carb.
Some carbs also have check valves in them some don't.When you take the bulb off that little brass bit is a check valve.

When I first started the carb rebuild kits would have check valves in them and the repair tool kit came with punches to remove & replace them.
Now day the carb gets tossed.

You can order in the base ( metering chamber housing ) that has the check valve in it but generally it is more expensive than the replacement carb

Walbro have a wonderful web site with pretty pictures & diagram showing exactly how carb cabs work & where all the bits are so if you really want to know then search for it.
The manuals & even videos have a link in the bottom right hand corner of the page where they are hard to notice .
And before you tell me it is a Zama / Ruixing or Wing Foo, they all work exactly the same regardless of the brand and in fact, a lot of parts are interchangable between brands.
Two types of cube carbs, butterfly throttle & rotary throttle, the brand name means nothing.

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Fish said:

Carb Kit....

4180 007 1060 CARB PARTS SET (FS110) C1Q-S72 $28.90

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