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2023/12/26 15:16:07
hazzardous

Tecumseh OHSK70 engine won’t rev

I bought a John Deere 724D snowblower non running.  The previous owner had definitely been messing with it.  It has a 7hp Tecumseh motor OHSK70.  The engine starts on choke but will not rev out on its own.  It dies when choke is off.  It will rev if I manually move the governor arm.  I’ve cleaned the carb, tried a second carb, adjusted the valves, tried a different coil, and adjusted the governor with no luck.  I’ve also verified the flywheel key wasn’t sheared.  Compression was 120psi.    I’m at a loss.  Any suggestions?  Is the governor broke inside the motor?
11 comments Leave a comment
SRTsFZ6
Is there tension against the throttle (engine off) from the governor arm/linkage?
 
Did you adjust the governor with the throttle wide open and the shaft the goes into the engine
twisted and locked down in the same direction as the carb throttle?
 
Usually, when the governor breaks internally, the RPMs go way up above 3,600 RPMs.
 
Does the machine have a throttle adjustment for the operator?
 
.
 
2023/12/26 19:11:42
SRTsFZ6
Also, if you post the complete engine model # you can bring up a parts digram.
Being it was messed before you got it, I'd bring up the parts picture and look for 
any missing parts the PO left off, put on incorrectly, etc..
 
 
https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/tecumseh/4-cycle-horizontal/ohsk-70 
 
 
.
2023/12/26 19:15:06
hazzardous
There is an adjustable throttle on the snowblower. When the engine is off and the throttle is down there is no tension on the linkage. Yes I adjusted the governor with the throttle wide open. Before I start the snowblower and the throttle is on high the governor arm is maxed where I set it but once the engine starts it backs off if that makes sense. I tried tensioning the springs more as well
2023/12/26 19:17:09
hazzardous
Ohsk70-72516d
2023/12/26 19:18:25
SRTsFZ6
Just to be clear, with the engine off, is the governor pushing/holding the throttle wide open?
 
.
2023/12/26 19:19:44
hazzardous
When the engine is off and the throttle is down the governor arm has play/is not holding the throttle wide open.
2023/12/26 19:21:57
hazzardous
Yes that’s my engine
2023/12/26 19:23:48
SRTsFZ6
hazzardous
When the engine is off and the throttle is down the governor arm has play/is not holding the throttle wide open.



There should be tension holding the throttle open.
 
The higher (more RPMs) you adjust the throttle, the stiffer the throttle will be with the governor. 
 
Look at the engine pic's on the link, and see if your missing anything.
 
.
2023/12/26 19:27:35
hazzardous
If there is tension holding the throttle open when the throttle is down then there would be no idle adjustment or adjustment when the throttle is on high. Shouldn’t the stop on the butterfly of the carb be on the idle screw when throttle is down? Every video I saw on YouTube shows the linkage just like mine with the throttle down and up. Spring is loose with throttle down and tight at throttle up. The one spring going to the governor arm on mine does appear to have a bigger loop than a new one on eBay though.
2023/12/26 19:44:46
micl8
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2024/01/02 13:54:56

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