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no spark


peted's Avatar
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12-15-03, 04:20 PM   #1  
peted
no spark

I have a snowblower with a 7 hp tecumseh engine (h70). This season, it does not want to start. I determined that there is no spark at the plug. The magneto and plug wire looked warn so I replaced that, and replaced the points, condenser and plug as well. Still no spark. I disconnected the kill switch wire but that didn't work. I also cleaned off the contacts on the inside of the flywheel and on the magneto. I suspect that the problem might be with the gap between the flywheel and magneto. The keyway seems to be good (no play). I'm not sure how to properly set the gap. I loosened the two bolts that hold the magneto in place and played with that, but am not sure if I'm setting the gap properly. Any help is appreciated.:(

 
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12-15-03, 04:45 PM   #2  
Place a buisiness carb inbetween the magnets and coil. That should be about right.

 
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12-15-03, 09:51 PM   #3  
Hello peted!

I wish I could have been there to stop you before loosening those screws. Getting it set up correctly is kindof a pain. There is a lengthy procedure for this which is described in the repair manual for this engine. Check at the library or an auto parts chain store like autozone or advance for a manual for small engines. Usually the piece that holds the coil never moves, so it doesn't need adjusting as regular maintainence. It should only need adjusting when it has to be removed for coil replacement or something like that. What did you set the points to? Did you set them while the engine was in the proper position? Have you checked the ignition kill wire?


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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12-16-03, 02:01 PM   #4  
peted
I set the points to .020". I also removed the kill switch wire and tried to start it, but to no avail. Also, trying to re-adjust the coil was done as a last resort. It wouldn't start befor that.

 
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12-26-03, 04:21 PM   #5  
peted
Finally got around to working on the snow blower again, and I have solved the no spark problem. The engine still will not start though. I believe it to be a problem with the carb. When I try to start it, I get an occasional sputter, and puffs of smoke from the exhaust and carb throat, but that's it. I tried spraying engine start fluid and some gas in the spark plug hole, but it won't even start for a moment. Need help!

 
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12-26-03, 08:59 PM   #6  
peted
When you go into ignition...it gets a little detailed, reason being as soon as you loosen the stator bolts the ignition timing has been disturbed.First off i would suggest that you get the TecumsehMechanics Hanbook part # 740049 from your local Small motor dealer cause it explains everything in very good detail.
For your H70, it states that your timing should be set at .080 BTC and you will require a dial guage to set it properly. It is very tricky to set cause you can be very close to the setting and as soon as you tighten the bolts it might throw it off by several thousandths of an inch and you don't want that. If you've got it apart, you might as well so it almost perfect. What I mean be perfect is I'm usually within .002 of the factory spec and I know you can do it also.
If that is correct and you figure that it is the carb, get the appropriate carb kit, strip your carb to bare bones and soak it in an approve "carb cleaner" not just varsol cause that doesn't do anything but clean the outside, and install the complete kit including the welsh plugs.
Main thing to make sure of is that your orifices inside the carb are clean and open before reassembling the carb.

The problem you have is not uncommon to me, I made a tool to check the spark and when I check the spark, I set it to jump at least 1/4 inch to make sure I got what I want and then I go from there.
I hope this helps you and if not let me know cause I will be checking on this forum daily.

snoman

be cool

 
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12-26-03, 11:45 PM   #7  
snoman is correct. Good advice!


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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12-29-03, 02:59 PM   #8  
peted
thanks....... I'll let you know how I make out

 
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