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Toro 421 Model 38010,TECUMSEH MODEL HS40-55513G


Arkman's Avatar
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12-13-10, 09:39 AM   #1  
Toro 421 Model 38010,TECUMSEH MODEL HS40-55513G

Hi everyone, I'm new to the forum but so far I've found a lot of great info. Thanks everyone that contributes.

I've gotten my snow blower fixed up a bit but I've got one more hurdle. But first let me give you some background info. This thing is older than I am and it sat for a while. Over the last 15 years its been used a handful of times and always started. I've actually had it for 3 seasons and I've had very little problems with it. Up until now just a leaky fuel line. I fixed that last season. This season I pulled it out of the shed and it started within 4 or 5 pulls. That was normal even on really cold days. The first snow it worked fine. The second snow it would die every so often, but if I primed it no problem it would fire right back up.

I suspected an air leak of some kind. So I decided to tear it apart and clean up the carb (since it hasn't been for a long time). I did the carb service and fixed a leaking fuel hose which I suspect was the issue. Now when I prime I can feel the fuel being sucked in, before i could feel/hear it really just sucking air. I thought I was in the clear, then after I got it back together it won't start very well.

Right now if I get the engine started it will stay running if I have it choked until is starts to choke itself out. This seems normal to me.

The problem is when I take the choke off. The engine seems to rev up extremely high. I'm not really sure because I don't really have a good way to test the RPMs but they seem extremely high. I think I found someone on this forum say that the idle rpm should be 1700 and the high should be 3800.

As it runs I'd guess that the idle is closer to 3000-4000. Now thats a total guess based on the sound of it and what I know of other small engines (not much).

My initial thought was I just needed some carb adjustment but so far I'm not having any luck. Its a pain in the butt to start and when I get it started it either dies to fast to mess with the carb or the engine revs up high enough I feel the need to kill it...before it kills me.

So far I've mainly tried adjusting the power screw. Its labeled as part 22 in this diagram.

I haven't adjusted the idle screw (#24 in the diagram) really but I could try that too I suppose.

The short version of this long story.
It starts really hard and revs up way high without the choke.

Does anyone have any ideas? I know with my boat motor carb there was suggested settings for the idle screw. Does anyone have any idea what that would be for this beast?

 
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indypower's Avatar
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12-13-10, 11:35 AM   #2  
The setting for both high & low speed is 1-1/2 turns out from lightly seated. Also make sure the holes in the jet (the "bolt" of item#2) are clean. There may be a tiny hole in the threads that most seem to miss.
Also, the primer line has no gas on it. It just pushes air into the carb to force gas in the carb to the ventury of the carb (kinda flooding the carb).
Idle speed should be about 800 rpm and full speed 3400-3600 rpm.
I suspect the linkage is not installed correctly.

 
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12-13-10, 11:38 AM   #3  
Check the butterfly/throttle valve, item #3 in your diagram, listed as "shutter" to make sure it is not stuck wide open.

 
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12-13-10, 11:56 AM   #4  
Posted By: indypower The setting for both high & low speed is 1-1/2 turns out from lightly seated. Also make sure the holes in the jet (the "bolt" of item#2) are clean. There may be a tiny hole in the threads that most seem to miss.
Also, the primer line has no gas on it. It just pushes air into the carb to force gas in the carb to the ventury of the carb (kinda flooding the carb).
Idle speed should be about 800 rpm and full speed 3400-3600 rpm.
I suspect the linkage is not installed correctly.
As for the primer, I think I know what you mean. I think the primer is fixed now and I just didn't explain what was going on with it before very well. Thats for the info. My carb on my boat motor was 4 so I'm glad I found out its 1 1/2 turns on this one.

I'll check the little holes. I think I know what you are talking about there.

As far as the idle linkage. I didn't even think of that. When I took it apart I forgot to look at what hole on the linkage was in on the shutter shaft (part 1). When I put it back together the first time it wasn't right. The second time I thought I got it right but it could be that its wrong. I totally forgot that I did that until you guys mentioned it.

Thanks again for the help. I'll take a look hopefully tonight and see what I find. I'll let you guys know if it worked or not. I sure hope it does.

 
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12-14-10, 06:30 AM   #5  
Well last night I checked the throttle linkage and it seemed to be in the proper spot. I'm not really sure though. It didn't seem to matter what hole I put the linkage in the shutter assembly either one it did the same thing.

I also made sure the jet was clear in that bolt like you mentioned and turned the screws out 1 1/2 turns each. When I did that I got it to start but it was still revved up really high. I turned down the power screw and got it to a point that it would stay running and sort of surge between a more normal rpm and a high one.

I tried adjusting it a bit more but then it would just die. I tried the idle screw as well but I couldn't figure out what was going on.

 
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