Small Engines (Lawn Mowers, etc.): toro ccr2000 backfire, assembly drawings, exhaust port

Question
I have a 1993 Toro ccr2000 snowthrower model # 38180 serial#3903997. I purchased it new in '93 and never a problem till this year. I always ran it dry and use fresh gas . This season it was backfiring and very hard to start and keep running,so I thought it was starving for fuel. I bypassed the fuel filter and it started up fine.  But the backfiring is still there. It will backfire for two minutes and then run fine. But it seems to have less power. Why is it backfiring and loosing power Thanks for listening, Gary

Answer
Hello Gary:

You can View a Breakdown/IPL of the Mower at this Site Addy, https://lookup3.toro.com/partdex/default.cfm and Select Start Parts Viewer. Now Enter the Model Numbers (38180) and Click Search. Now Select View Assembly Drawings for your Year Model. This is a 2 Cycle Engine. Did you Check the Exhaust Port and Muffler? If Either of these are Restricted with Carbon Deposits, then the Engine May Run at Idle but will Flood and/or Cause Backfiring when you Try to Rev the Engine above Idle. The Following is a Basic Instruction File for Doing a Diagnostic on the Engine for this Problem. Any Input is Appreciated. **Remove the Muffler and Make Sure the Exhaust Port is Clear. If it is, then Try to Start the engine with the Muffler Off. If it Starts and Runs Properly, then Clean the Spark Arrestor Screen in the Muffler or Replace the Muffler if Required. The Back Pressure from the Blocked Exhaust Port or Muffler Causes the Engine to have too Much Fuel Mix in the Cylinder Due to Improper Exhausting of the Cylinder. The Heat Expands the Metal of the Exhaust Port and the Muffler and this Allows for More Gasses to Exhaust; although Not Enough for the Engine to have Proper Power, but Enough for the Backfiring to Stop. 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. Comments and Ratings are Greatly Appreciated. Thanks.

Respectfully

John