MTD / Yardman snowblower engine

C

Cfs

Well-Known Member
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

Spit
 
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?

Do you have more than 50 PSI compression?
 
Auto Doc's said:
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.
Click to expand...
Agree with Auto Doc's.

There are cheaper tools out there than the below one. IMO, that is the best out there.

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I have it running again. I checked it with a new leak down tester and it was great under 10 %. I removed the rocker arms to assure the valves were completely closed. I reset them to .005 intake and .007 for the exhaust. I also ran the carb through an Ultrasonic cleaner. And I went ahead and changed the coil. Since it was pointing that way. It started on the 3rd pull and ran fine. A little smoky at first no doubt from the attempted starts earlier with the weak coil.
Thanks to everyone
 
So. I have another issue with the blower. The throttle lever does not not affect the engine speed. It runs at full throttle regardless where the lever is set...low or high setting it runs at full throttle. To be clear it is not running out of control dangerously fast, just at full speed. I asked the owner if he was aware of this being an issue before he brought it to me. He said no. I assume he is correct but this is the first I have been able to get it to run and see this problem. It may be that I disturbed something in the 2 links from the governor to the carb and the throttle link fro! The governor arm to the throttle control. All of this is under the fuel tank. I did remove the fuel tank to get the blower housing off so I could install the coil. Anybody ever have a similar situation? Or know what I should be looking for? I don't believe that I mis-installed anything but it is very hard to find good illustrations of the correct locations of the links on the governor arm which is covered with holes..but I don't think I disconnected anything at least not deliberately

I'm sure that it should be fixed but there really is very little reason in my mind to run a snowblower at low speed. Is there any potential harm to the engine if it is not corrected? And it is allowed to run like a single speed lawnmower engine?

Spit
 
Sounds like a governor pull back spring is in the wrong hole or came out of place. It is not good for these splash oiled engines to go right to full RPM without a proper warmup. That will give a real "exploded view" of what the engine looks like inside.
 
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