Vacuum & pressure tests

[johnny newburgh]

 While troubleshooting a saw I learned that you can diagnose issues using a vacuum/pressure gauge. You can check carburetor gaskets diaphragm needle purge bulb etc. Fuel line, Gas cap, Intake,Impulse line, crankshaft seals , base gasket, case. Carburetor tested good.Found a vacuum leak on crankshaft seal clutch side. Checking fuel line/ gas cap looked ok.Pulled vacuum through line and when I held my finger over vent hole vacuum held and when released vacuum dropped. Holding pressure indicates fuel line/ tank was not leaking. When I released finger on gas cap vacuum dropped telling me cap was venting. Thought line was clear because of vacuum bleeding off but that was not the case!! When I was trying to run saw It would not stay running unless choked so I figured It was not getting fuel but I had tested with gauge? So I pulled fuel line/ filter and I found the plastic elbow coming out of tank was clogged. When I used vacuum test I put 5-7 HG and I guess that is a lot more then the engine creates when running. So vacuum/pressure test Is great but beware

[Texas-Jim]

Vacuum and pressure testing is probably the best tool we have to find faults.

[Mountain_d]

I would like to try this. Johnny and others that do this, can you give us a description of the tool you use for this so I can buy the right stuff? Thanks. Mountain.

[weimedog]

Couple of Vac Text tips.
https://www.youtube.com/watch?v=ZjU4kh84mkA

Actually, contrary to what I said in the video; the "CST" did throw a hint or two....

https://www.youtube.com/watch?v=OfXBmam97bM