Small Engines (Lawn Mowers, etc.): poulan chainsaw, poulan chainsaw, line pumps

Question
saw will not start. spark is good, gas is good, compression is good,all gas lines are good.the only thing i noticed different there is no pressure when i remove gas cap. could this be the problem? if so how do i fix it. by the way how and why dose pressure build in the gas tank.

Answer
Hello Tony:

Remove the Muffler and Inspect the Exhaust Port for Carbon Blocking the Exhaust Port. Check the Muffler and Spark Arrestor Screen (in the muffler) for Blockage Also. If the Exhaust Port or Muffler are Clogged, then the Engine Can Not Draw Air/Gas through the Carburetor and Into the Cylinder. The Gas Tank Cap is Designed to Allow Air in Only. The Difference in the Air Temperature and the Engine Temperature Causes the Gas to Expand and Pressure Builds in the Tank. The Return Line Pumps Slightly Heated Gas Back Into the Tank from the Carburetor. You can View a Breakdown/IPL of the Mower at this Site Addy, http://hayward.arinet.com/scripts/EmpartISAPI.dll?MF&app=ASP&lang=EN&TF=Mainfram... and Select the Catalog Poulan/Weed Eater. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. Have a Happy Holiday Season and May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John