# ????? carb will not prime



## twocycle (May 29, 2017)

Craftsman blower 358.79701, the primer stopped working, took off carb used carb spray cleaner and air to blow out all the passages. Put it back toggether with a new gasket and diaphram, would not prime and the bulb split. Replaced the bulb still wont prime, tried loosening gas cap, nothing. Got any ideas?????

Dan


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## nbpt100 (Jun 1, 2015)

I am not familiar with your specific machine so I can only provide generic advice. Make sure you put the fuel lines back in the correct locations. It can be easy to mess them up. If you have clear lines you can watch the gas being pulled up in the the carb. when you prime. Depending on the carb design it may also have a return that will return gas from the carb back to the tank. There is a check valve on the primer. It may also be bad. Double check that that lines are correctly routed first.


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## twocycle (May 29, 2017)

Had same problem before CiU-W43B carb rebuild. The machine is a Craftsman 25cc yard blower, the bulb compresses but will not fully fill. Check lines as compared to my other gas machines and is correct, even tried switching them no difference. Is there some kind of check valve in the C1U carbs ?? This thing is wiping me.... lol

Dan


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## nbpt100 (Jun 1, 2015)

Again I dont know your specific carb but it usually is a rubber piece right below the primer bulb. Sometimes it is a silicon orange color. Try to get the the exploded assembly drawing or the parts list for the carb and search for a check valve or one way valve.


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## finaprint (Jan 29, 2006)

That rubber silicone piece is a check valve, it not sealing the primer will NOT work.


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## bob1190 (Apr 18, 2010)

finaprint said:


> That rubber silicone piece is a check valve, it not sealing the primer will NOT work.


Ditto. Several check valves can cause this. Might get lucky and find one online relatively cheap.


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## ragsdalesmallengine (Nov 27, 2017)

I believe that is a purge pump primer, I've had some success connecting a Mityvac to the inlet side of these and pumping it a few times. It should draw a vacuum. If it's not doing that I'd say your check valve is no good or you've got a leak in one of your hoses.


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