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Discussion Starter #1
Hi, I helped a neighbor out with their barely used Craftsman 247.889720 snowblower. They had it sitting for 16 months and it would not turn over.

I took off the carb and cleaned - the varnish inside was worse than I could imagine (I have a Craftsman 5/22 from the 80s that looked better!). There was varnish in the bowl, and through all the tiny jets inside.

I sprayed Deep Creep (all I had on hand for "carb cleaner") and used a small needle and cleared all the jets I could find. I was able to get it running and it seemed to work great.

After longer use I've noticed the idle seems way high and the throttle lever doesn't affect the idle speed through the range at all - just Off in the off position or high idle in any other position. When we both used it yesterday after a storm we both experienced afterfire when moving the lever to Off when done using the snowblower.

I also noticed that the choke control seems to work strangely: when the engine is cold, you put it on choke in order to get it to turn over. Then after a few seconds, put it in the next position, and the RPMS go up, then the 3rd position it goes up even more, then in the last position the RPMS drop a bit. Once the engine is warm, if I try any of the positions other than WOT, the engine sounds like it's going to stall within seconds.

I don't know this engine/carb well - but I'm pretty sure I put it all together right with throttle linkages and choke control.

A couple things I could think of:
I appreciate any help/advice in advance!
 

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After longer use I've noticed the idle seems way high and the throttle lever doesn't affect the idle speed through the range at all - just Off in the off position or high idle in any other position. When we both used it yesterday after a storm we both experienced afterfire when moving the lever to Off when done using the snowblower.
So the throttle lever moves, but basically changes between two speeds? Just idle, and full-RPM? That sounds like a possible issue with the governor, and its linkages/spring.

I also noticed that the choke control seems to work strangely: when the engine is cold, you put it on choke in order to get it to turn over. Then after a few seconds, put it in the next position, and the RPMS go up, then the 3rd position it goes up even more, then in the last position the RPMS drop a bit. Once the engine is warm, if I try any of the positions other than WOT, the engine sounds like it's going to stall within seconds.

You were talking about the choke, but then mentioned WOT. Are you referring to a choke position? Or do you mean that, once the engine warms up, it will only run at full-RPM, regardless of the choke setting?

I don't know this engine/carb well - but I'm pretty sure I put it all together right with throttle linkages and choke control.

A couple things I could think of:
Try adjusting the idle stop screw if you want. It shouldn't really hurt anything. That should control how far the throttle plate can close, which sets your low-RPM speed.

Hopefully that spring is fairly accommodating, and can handle some stretching. But I don't have experience with this engine/carb.

I doubt that would be an issue. If you want to check for air leaks at gaskets, start the engine. Now spray carb cleaner, or something similar (a flammable spray) around where the carb mounts to the engine. Spray it on the gasket, etc. If you have an air leak, the engine sound will change as you spray, due to the spray being drawn in at a gasket. You can also try spraying at the top of the throttle plate shaft, where it goes into the carb. Sometimes you can have an air leak there as well.
 

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Thanks for the response, sorry for the delay in getting back to you:

So the throttle lever moves, but basically changes between two speeds? Just idle, and full-RPM? That sounds like a possible issue with the governor, and its linkages/spring.

>> Actually only one speed - it's either off, when the lever is fully to the right, or "on" at full-RPM anywhere else in the range.


You were talking about the choke, but then mentioned WOT. Are you referring to a choke position? Or do you mean that, once the engine warms up, it will only run at full-RPM, regardless of the choke setting?

>> I think I used the wrong terminology. When I say WOT, I meant the choke position that is furthest from the choke fully engaged side. My understanding is that put it on full choke to start it, then as it warms up, click the choke over one notch to keep it from stalling until you can move the knob all they way to the other side (4th position). I would have thought the RPMs would keep climbing as you click the choke over as it warms up, but that it was strange that it drops from position 3 to 4. It made me wonder if the butterfly was in the wrong position when I put the carb back on to the connecting arm...


Try adjusting the idle stop screw if you want. It shouldn't really hurt anything. That should control how far the throttle plate can close, which sets your low-RPM speed.

>>I will take a look a look at this too when I get the machine in my hands again.

Hopefully that spring is fairly accommodating, and can handle some stretching. But I don't have experience with this engine/carb.

>> I would hope so, thanks for the vote of confidence.

I doubt that would be an issue. If you want to check for air leaks at gaskets, start the engine. Now spray carb cleaner, or something similar (a flammable spray) around where the carb mounts to the engine. Spray it on the gasket, etc. If you have an air leak, the engine sound will change as you spray, due to the spray being drawn in at a gasket. You can also try spraying at the top of the throttle plate shaft, where it goes into the carb. Sometimes you can have an air leak there as well.


>> Great idea, I would hope this isn't it either!.
 
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