Walbro pump diaphragms come in several flavors. Each type has pros
& cons. Here is a list of the types and how they differ.
WALBRO SCREEN FILTER
A very common problem with Walbro carbs is the internal filter screen.
This screen has about a 1 to 2 micron mesh and its very effective in keep trash out
of your jet stream, however the price you pay is a clogged filter screen.
Indications of this filter being clogged is; hard starting, and having to re-tune the
needles to get it to run right. As the filter clogs more the symptoms get worse.
Here is how you replace or clean the filter:
(1) remove the pump cover. The pump cover is held in place by a single screw in the center
of the cover.
(2) carefully remove the pump diaphragm & gasket.
(3) carefully lift the screen out with a knife or Exacto
(4) clean the screen or replace it, and re-assemble the carb.
(5) adjust the needles back to factory settings. Adjust as needed.
Based on experience, I've found it difficult to clean the screen back to 100%
effectivness, therefore I usually replace them. micron sized particles are very small and
wedge in the screen very tight.
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