Lots of small 2 Stroke carbs not priming with primer bulb.

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Fordiesel69

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Sep 10, 2005
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For those that are very familiar with small stroke Zama, Walbro, and chinese clone carbs, what is the reason you cannot get them to prime when pressing the primer bulb?

I have had to replace the whole carb just because of this and no fault has ever been found.

I have a really mint green machines 4600k leaf blower that has a nice walbro carb. The factory parts were all good but I put a $34 complete kit in it hopeing to solve the primer issue. Nope, same as before you have to spray fuel in the carb to get it going then it runs perfect.
 
There are a few things that can cause this:

-Passage inside carburetor is clogged
-Primer bulb itself is cracked or rotted
-Fuel lines have cracked or hardened, especially where they meet the tank and aren't sealing properly
 
I wonder if using ethanol enhanced fuel is wreaking havoc on the fuel lines or primer bulb or gaskets... Do you use ethanol fuel?

Just my $0.02
 
Nope. Its a pattern I have been experianceing on many carbs. I just gave that recent example. It must be somthing i'm missing.
 
Could be also "chinese" 2stroke oil residue in a carb (from test run in a factory)....residue can gunk tiny passages...glue up membranes inside etc.
Especially if OPE sits for a year or two in a warehouse....

Take carb appart....blow everything with compressor....and if all that doesnt work....put a new set of membranes in it.
 
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Have the same issue with a Stihl FS90R. Factory primer bulb split so I installed a new one. It will no longer prime with the new bulb installed. Nothing else was changed on the carb. You can still get it started by choking it and pulling it about a million times but once its running its good.
 
CDX825 said:
Have the same issue with a Stihl FS90R. Factory primer bulb split so I installed a new one. It will no longer prime with the new bulb installed. Nothing else was changed on the carb. You can still get it started by choking it and pulling it about a million times but once its running its good.
Click to expand...
This is exactly what im talking about. 100%

Its not debris or clogs as I ultrasonic them to no avail either.....
 
Describe what happens with the bulb ...pressing it either just air in it or the bulb is full of fuel and is hard to press? If no fuel in the bulb check the lines as many have said and check behind the bulb there is small check valves that may need priming. If bulb has fuel but wont press then hose th carb throat is clogged.
 
check integety of the gas tank fittings and fuel lines and fuel cap . it must be airtight for prime /air purge. when ever I have a mystry no prime issue-its always one of these
 
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