Earlier this season it was surging even when idle, died slowly under load. I removed and cleaned out the carb and replaced the gaskets. It has been running great for several weeks.
Today my son cut the front yard fine. An hour later it started and idled fine. Then when he pushed down the bar to engage the blade, it died quickly (no surging etc.). Removed carb, checked the linkage all looks good. Removed blade, cleared some built up grass etc. With the spark plug wire removed and the bar engaged, the blade turns freely. Tried to restart, same thing. Runs great in idle, dies quickly when bar is engaged. This mower has self propel, but I do not have it in gear when it dies.
I haven't work on one of those engines in many years, if you didn't know it is a 1985 model. 31 years means you have maintained it very well. I believe you have either a carb or governor problem, leaning toward carb. If it came into the shop, would pull the carb and give it a good ultrasound cleaning, or in your case a 24 hour bath in carb cleaner. Replace any parts which might be questionable and reassemble. When reinstalling I would use all new gaskets, as from your description, I would be looking for an air leak. Also check that the insulator is installed in the correct direction and does not have any hairline cracks. When you have it idling after you've done this, slowly open the throttle using the governor arm, not the throttle control. What you are looking for is a point where it starts to stall out and at the same time you should feel resistance on the governor if it is working properly. This may end up being a slow process, as there may be other reasons for the problem, but we have to start somewhere. I've added a couple of manuals which might be of help. Let me know what you would like to do and if you need more help.
Thanks for your input Rivets. I made the 2 gaskets out of thin cardboard. Do u think that might be an issue? Also what is the insulator that you mention?
Look at the parts breakdown of the carb in the manual I posted for you. It goes between the carb and the engine body. Also, this insulator must be install in the correct direction and I would get the proper gaskets, as these old 2-cycles are very touchy.
I was thinking items #2 and #15 for sure. Inspect the insulator, #14 and replace if any cracks.
What about gaskets #12 (2 of them it seems). Replace them as well?
#7
BlazNT
81-2320 need 2 Insulator Gasket
81-2190 need 1 Insulator
81-0780 need 1 Carb gasket
Exploded parts view. Part numbers on view is 15-12 ereplacementparts.com/toro-20684-500000159999991985-lawn-mower-parts-c-121776_127291_128204.html
I always like to wipe a greasy finger over all gaskets.
Note I did not say to put grease on the gasket just a smeere.
This has on effect on the sealing but will allow it to strip clean when next removed.
High temp axel grease is the go not LM or graphite.
Sorry I've not gotten back to you, but 9-10 hour days make my time limited. Bert and Blaz have got you pointed in the right direction, follow their advance. I'll continue to watch and chime in if needed.
