I am trying to help a neighbor with his Yardman model 31AS62EE708. It has a MTD engine 265-SU serial 1005284B0327. It's 15 yrs old. I assumed it was a typical old gas dirty carb situation. Owner said it would start and die after a few pops. Now after cleaning the carb, it will start after 6-8 pulls and runs super slowly about 1pop a second..super slow it cannot gain any speed and smokes a lot. Taking it off choke or moving the throttle to a higher or lower speed doesn't increase the speed and the engine will usually die after 30 seconds or so. I have pulled the carb and cleaned both jets.. high speed and low speed as well as the emulsion tube. I have cleaned and repaired a lot of these 'Honda' style carbs and I am sure it's done correctly. It seems to have good spark as far as I can tell using tester that lights up when it gets an impulse. I have installed a new spark plug too. I have set the valve lash to .006 for both. Maybe .008 would be better for the exhaust valve. I have not tried to check the compression but I will tomorrow. I am assuming that the coil is good since I have spark...do coils ever breakdown and only spark half of the time or less? Maybe the 6-8 pulls builds up enough compression maybe from the excess uncombusted gas in the cylinder? But due to low compression it will not run anywhere near full speed?
A couple of asks...Does anyone have a shop manual for a 265-SU
What results should I expect to see for compression for this single cylinder horizontal 4 cycle OHV.
I welcome any and all ideas and comments on what I should try to troubleshoot and hopefully repair this snowblower...I am really stumped but I am hoping its something simple that I have never run into
Don't use a "Christmas light" style spark tester, use and open air one with the adjustable air gap. With the gap style you should see a consistent bright blue spark and that will verify the coil operation.
I know you set the valve lash, but did you verify both valves are opening about the same about?
Don't use a "Christmas light" style spark tester, use and open air one with the adjustable air gap. With the gap style you should see a consistent bright blue spark and that will verify the coil operation.
