A Quick Question About Pressure Testing A Carburetor

[iknowashortcut]

Hi guys, I wanted to ask a quick question that I'm pretty sure I know the answer to but just wanted to verify. Does a carburetor have to be airtight in the same way the crankcase needs to be? I recently picked up a 025 project and when I pressure tested the carb it had a small air leak around the gasket on the side between the fuel pump cover and the carburetor. Not a bad one, but enough to fail the pressure test and I wondered if this would cause symptoms similar to air leaks in other places. Thanks again in advance.

 

[AVB]

Yes in a way as the fuel pump will not work as well, air can be drawn in causing lean outs and when the saw sits with the fuel tank pressurized will leak fuel out. Replace the gasket and pump diaphragm if it is failing the pressure test.

 

[iknowashortcut]

That's about what I figured. Thanks much for the help.

 

[Whitty21]

I have never pressure tested a carb. That being said, any time you get used saw its always a good idea to throw a carb kit at it for the 5 minutes it takes to do

 

[iknowashortcut]

I have never pressure tested a carb. That being said, any time you get used saw its always a good idea to throw a carb kit at it for the 5 minutes it takes to do

I agree. That's what I've usually done. Having pressure tested it, though, I can say with some degree of certainty why it actually needed to be done versus just doing it because it's just a good idea. My awkward attempt at trying to turn the experience into a learning one.

 

[AVB]

I have never pressure tested a carb. That being said, any time you get used saw its always a good idea to throw a carb kit at it for the 5 minutes it takes to do

Sure saves time and gives peace of mind when working on those flooding carbs. I had several carburetors where the needle seat itself was at fault and the leakage only showed under pressure testing. These had to be replaced as the carburetor kit would never fix the problem.

I had Walbro, Zama and Ruixing carburetors all to have this problem. It doesn't take much to do the test even a small syringe works; although, a regular pressure/vac tester works best. You just stay below the pop off pressure.