Tecumseh HS40 cuts out when I try to accelerate

Rupp_It_Up

Rupp_It_Up

#21
#21
Skipp said:
I had a similar occurrence today idled fine under load or after a rev it would just die...a pull or two and it hesitantly fires....changed out the gas and it ran just fine...read somewhere recently not to keep ANY gasoline more than 30 days no matter the additive you put in it...ie stabil etc...just a simple thought...
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I initially thought is was gas problem but have the same issue with fresh gas.

The motor idles very smoothly and starts on the first or second pull every time.
 
M

Mariah

#27
#27
I feel your engine has a serious breathing problem (asthmatic). Check the valve stems for sludge and gum that's preventing it from moving freely, remove the breather and with the engine idling spray gumout on the top of the valve stems where they meet the guides, it the engine revs better you got it nailed. If that fails to help, the cam shaft is out of time with the crankshaft. Pull off the side cover and verify the cam timing is correct.
 
Rupp_It_Up

Rupp_It_Up

#28
#28
Mariah said:
I feel your engine has a serious breathing problem (asthmatic). Check the valve stems for sludge and gum that's preventing it from moving freely, remove the breather and with the engine idling spray gumout on the top of the valve stems where they meet the guides, it the engine revs better you got it nailed. If that fails to help, the cam shaft is out of time with the crankshaft. Pull off the side cover and verify the cam timing is correct.
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Thanks for the response. I did check the valve stems when I pulled to breather last week and everything looked clean, but it's your suggestion is worth trying. What really has me stumped is that the motors idles perfectly and upon acceleration it does seem to have a breathing or spark issue. I assumed the cam shaft timing is correct based on a smooth idle.
 
M

Mariah

#29
#29
I had and antique engine with valves that would rock back and forth 1/16" . It idled a lot and was running on old stale gas, one day it quit and coasted to a stop. Much to my surprise the intake valve was stuck wide open, the stem looked clean but it was stuck fast! Using small vise grips on the valve stem and lots of gumout, it took me a whole hour to get it loose. That was a major education for me about stale gasoline and what it can do!
 
Rupp_It_Up

Rupp_It_Up

#31
#31
ELT said:
Two things come to mind. A bad condenser will allow an engine to idle but not accelerate. Just because it's new doesn't mean it's any good. Have you tried a diffrent spark plug?
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I did try a new spark plug and another new condenser with no luck. I did notice the points didn't close perfectly flat and will try to fix that next.
 
Rupp_It_Up

Rupp_It_Up

#32
#32
I'm hoping I found the culprit tonight....
I noticed the timing & points gap seemed to go slightly out of adjustment after everything was tightened down and the motor was started. So I checked the ignition cam it fits kinda sloppy on the crankshaft. I'll replace it tomorrow and hope that solves it.
 
U

ubernoob51

Active Member
#33
#33
I had a similar issue with the HS40 on my Rupp Roadster, turned out to be an ignition issue. I set the points gap to 0.020” then set the points to open at 0.065” BTDC, then it ran perfectly. Hope this helps.
 
massacre

massacre

#34
#34
ubernoob51 said:
I had a similar issue with the HS40 on my Rupp Roadster, turned out to be an ignition issue. I set the points gap to 0.020” then set the points to open at 0.065” BTDC, then it ran perfectly. Hope this helps.
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I think you may have the BTDC measurement wrong,
IIRC it is .035” BTDC, but the dial indicator will read .065” ;)
 
markus

markus

Well-Known Member
#39
#39
ubernoob51 said:
Huh. Well it runs well, so I’m happy with it. Where did you find the ignition timing information?
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Page numbers in the 90's of this version of the L head service manual show the specifications......make sure you looking at the specs for the points engines as the electronic ignition units wont show the timing specs...... .065 is what the H25-35 of the 1970's and ealry 80's with points used.

http://www.smallenginesuppliers.com...cumseh_L-Head_Engines_Service_Information.pdf

Glad it runs for you, not sure how its doing it but thats cool!
 
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