# Need help on Tecumseh engine



## jmclester (Aug 30, 2011)

I have a generator that is about 15 years old that is operated with a 10hp Tecumseh gas engine with a rope pull starter. Engine cranks fine and runs about 5 minutes and shuts down. After cooling it can be restarted and runs about 5 minutes and shuts down. I have put new gas in tank, drained the carb bowl, replaced the fuel filter and spark plug and I get the same results. Any suggestions on what to try next?


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## geogrubb (Jul 28, 2006)

Try running it with the gas cap loose or off, it may not be venting properly. Have a good one. Geo


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## phillipmc (Jan 27, 2008)

Also check for spark as soon as it shuts down.


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## jmclester (Aug 30, 2011)

Tried running it with the gas cap off. Same shut-down after about 5 min of running....just like clockwork. Here is some more info:

Model: HM100

Had varnishing issues about 10 yrs ago and a friend put a carb kit in. I crank it every 2 months but probably should have changed the gas more frequently. Now it runs smooth (for 5 min) but I have to leave the choke about 1/2 closed to keep it from surging. Is it possible that "varnish" heats up to the point that it starves fuel and shuts down?

phillipmc - I was initially thinking your way when I tried a new plug. Here's another thought: I once had a Kohler Magnum 20hp that would run for 5 min and stop....cool down and restart and repeat the process. The problem was the ignition module. With the Tecumseh being a rope pull would it have the same type of module or coil or magneto? I mean since there is no battery to maintain?


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## 30yearTech (Sep 14, 2006)

jmclester said:


> With the Tecumseh being a rope pull would it have the same type of module or coil or magneto? I mean since there is no battery to maintain?


Electric start or pull start, the ignition system runs independent of the electrical system, although on some engines a battery may be required for the system to operate. Even on a unit that requires an external battery, the battery would have to drop well below cranking power before the ignition would stop performing.

Test for spark when the engine dies as suggested, this will either confirm or eliminate the ignition module as the source of your issue.

Having to use the choke to keep the engine running smoothly does indicate that your carburetor needs service, maybe not a kit, but at the very least some cleaning. The carburetor could still be your issue, but I am more inclined to suspect your ignition module.

Best of Luck...:thumbsup:


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## jmclester (Aug 30, 2011)

I may be getting closer. I have now noticed that the gasket inside the fuel cap has started to disintigrate. About half of it has fallen out in chunks and the only place to go is down into the fuel tank. Noticed also that the fuel level in the filter goes from almost full to about 1/4 full during the time that it's running. Still appears to be fuel at the exit of the filter into the fuel line but could there be a vacuum created in the fuel line created by a blockage or partial blockage in the tank that would cause fuel starvation at the carb? Any of this sound reasonable?

I can check for spark too though.


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## duffer72 (Jul 23, 2011)

A piece or pieces could easily block the out let from the tank, whenit shuts off it reduces the suction and probably lets the pcs move some allowing the fuel to flow again for a period of time, Had similar with my daughters car, found the fuel filter 1/2 full of crap, and it would clog the screen after driving a while and cauce it to shut down. I would yank the tank off and give it a goodflush out with clean gas and then try it again. would also replace the cap or gasket for it if it is available seperatly. godd luck. Some of the Tech engines have a screen at the tank outlet on the plastic tanks.


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## 30yearTech (Sep 14, 2006)

jmclester said:


> Still appears to be fuel at the exit of the filter into the fuel line but could there be a vacuum created in the fuel line created by a blockage or partial blockage in the tank that would cause fuel starvation at the carb? Any of this sound reasonable?
> 
> I can check for spark too though.


Yes, that's a reasonable assumption, certainly worth looking into.


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## jmclester (Aug 30, 2011)

Will try all this after the holiday weekend and post results. Many thanks for all the suggestions!


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## jmclester (Aug 30, 2011)

Ok I checked for fire immediatly after shutdown and it was there so that apparently rules out the ignigtion module. 

I cranked it several times Saturday with relative ease (while both hot and cold) and each time it ran anywhere from 3 to7 minutes (I timed it each time) and then sputtered and shut off. I'm leaning toward a carb problem since i have to choke it about halfway to get it to run smooth. When it shuts down there is usually a puff of blue smoke. Is it possible that, once the motor has "warmed up", it's running too rich and chokes down? Or is there something in the carb that, once the motor heats up, there is a constriction that causes fuel starvation?

Carb cleaning, carb kit? What do y'all think?


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## usmcgrunt (Sep 16, 2007)

Have you replaced the gas cap? If the cap is new,then you will have to clean the carb.If the cap is old,the vent may be clogged and stopping the flow of fuel from the tank.


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## jmclester (Aug 30, 2011)

usmcgrunt said:


> Have you replaced the gas cap? If the cap is new,then you will have to clean the carb.If the cap is old,the vent may be clogged and stopping the flow of fuel from the tank.


Have already tried running it with the cap off. Same problem occurs.

Will Seafoam help much or will this require a good thorough cleaning? I've never worked on a carb. Difficutly rating?


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## usmcgrunt (Sep 16, 2007)

Depending on how dirty the carb is,Seafoam will probably work,but will take time.As they say,there's no such thing as a mechanic in a can.It is more useful as a preventive maintenance tool AFTER the carb is working correctly.Here is a link to the carb I THINK you have.Just lay out everything on a clean rag in the order of disassembly and follow the directions at the link posted.Pay particular attention to the little holes in the jets and carb body.Brake clean and compressed air will be your best friend for cleaning.The wire from a bread bag twist tie is ideal for cleaning the small holes.Good luck,hope this helps!
http://outdoorpowerinfo.com/repairs/tecumseh_carb_632334a.asp


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## jmclester (Aug 30, 2011)

Thanks for the detailed diagram. That's my carb for sure. I'll take it slow and easy and take some digital photos before and during. 

Thanks again.


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