Tecumseh HH120 Won't Start

BlackMountian88 wrote:

Well my latest breakthrough suggests the plug is not getting wet. Even after I dump gas in the cylinder...

then it has to be leaking past the rings somehow.

What happened to 100psi compression?

That's the thing, it's got 100!

Pics are downloading now.

I still think its ignition

Here are the photos. I have no clue how it works, I just know it does. The second one was the closest thing to a magnet I could find. Just a flat spot on the flywheel.

I'm sure it has a magnet but it's just covered in rust

That's bizzarre. I want to know what triggers the ignition. Something behind the coil perhaps? Take it off and look.

I'm researching my brains out on this one, as I am intrigued. Parts and info are hard to come by, but it appears that the coil is a standalone part. There's a stator and magnet behind the flywheel- this is what times the spark. Still digging.

I have a completely disassembled hh120 at home that I could take some good pictures off of later today, just tell me what you want a picture of.

That's great WTS- Should be helpful- thanks!

OK... read this article and posts - there seems to me a few clues there -

http://www.doityourself.com/forum/outdoor-gasoline-electric-powered-equipment-small-engines/330115-tecumseh-solid-state-ignition-troubles-magneto.html

particularly Cheese's post and onward. I now remember Ive had an engine of this series before and had the same problems you do, it was spark related and the pickup coil had a lot to do with it. Trigger coil, etc - they go by a lot of names depending on who you ask. Theyre a reliable system, but over-complicated.

I encourage you to read that - it will most likely help.

prometheusedi wrote:

OK... read this article and posts - there seems to me a few clues there -

http://www.doityourself.com/forum/outdoor-gasoline-electric-powered-equipment-small-engines/330115-tecumseh-solid-state-ignition-troubles-magneto.html

particularly Cheese's post and onward. I now remember Ive had an engine of this series before and had the same problems you do, it was spark related and the pickup coil had a lot to do with it. Trigger coil, etc - they go by a lot of names depending on who you ask. Theyre a reliable system, but over-complicated.

I encourage you to read that - it will most likely help.

Overcomplicated, perhaps for a simple OPE engine- but ahead of it's time, as well. Modern CDI systems don't differ by much at all!

Simple and damn reliable. I've had quite a few 120's and never had an electrical problem yet. Although the external voltage regulator for the generator is hell to wire without a diagram.

this is good to know if i ever have problems with mine.. i have an HH100 on my bolens. same engine just 2 less ponies. never let me down. did blow the windings in the starter gen though... i doubt i'll be of any help, but i'll stick around.

Thanks everyone!

Thanks for that post Pro, I have read parts of that a few days ago.

WellThatsSuprising, Your pictures are right where I'm at now. Except I didn't remove the coil and such to that extent.

I don't believe it's adjustable, especially after seeing those pictures. I think I'm going to clean it up nice, and put it back together. There's not much else I can do.

Despite what yall say here, my dad is certain it's not a spark problem. I still think it could be ignition timing, but there doesn't seem that there is a way to adjust it.

Quote from Cheese:

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Ok, you have the oddball engine Tecumseh made as one of their early (maybe the first) attempts at solid state ignition. It actually worked pretty well, but it's more complex than necessary.

I have limited experience with these...there just aren't many around. Bear with me, and I'll give you whatever help I can. The stator is generally the alternator, and since yours is not alternator equipped, it would not have the stator.

BlackMountian88 wrote:

Despite what yall say here, my dad is certain it's not a spark problem. I still think it could be ignition timing, but there doesn't seem that there is a way to adjust it.

Well- I am inclined to think it's ignition related- whether spark strength or spark timing- and here's why:

-You said it has a measured 100psi compression. This is more than enough to support combustion, and eliminates stuck/bad/not sealing valves. To COMPLETELY eliminate valve timing as an issue, open it up and check.

-If you unscrew the plug, pour a teaspoon of fuel directly into the combustion chamber, reinstall the plug and crank, it should pop. (again, assuming valve timing is correct). Whether you get one good pop, or it actually runs for a few seconds, there should be something.

Combustion requires air, fuel, compression, spark, and timing. What's missing? Verify valve timing, and that just leaves spark timing, or a weak spark. You have air, you have fuel (poured in hole, worry about carburetion later), and you have compression.

Upon further thought- i believe your valve timing is OK. Why? Excellent compression.

Yes, that does seem like it. I don't know about exact valve timing, but it looks like it should. I can follow it through the different cycles just fine.

Is there anything I can do about the spark now? I'm going to be away most of the week, and I want to put as much as I can back together, as the tractor is stored outside.

BlackMountian88 wrote:

Yes, that does seem like it. I don't know about exact valve timing, but it looks like it should. I can follow it through the different cycles just fine.

Is there anything I can do about the spark now? I'm going to be away most of the week, and I want to put as much as I can back together, as the tractor is stored outside.

Read this - http://home.earthlink.net/~edstoller/id9.html and see if you can adapt his method.

It's what I'd do

Lots of good information there, but that doesn't address my engine.

One of the difficult things for me, is I do not own a digital multimeter. So It's hard to get accurate reading. Usually I just test, ohms, or voltage presence.

Digital multimeters are available cheap. Do yourself a favor and get one. Troubleshooting wiring sucks without one.

You don't need a fancy expensive fluke brand multimeter to take care of your tractor, an elcheapo from walmart or harbor freight will do fine.

I know, I know. I've only got $7 right now. I saw one at homedepot for $15. That's what stinks about being my age.

I'm sure you can find an odd job or 2 to do for $8. Cut someone's lawn, trim hedges, paint something. Make a youtube viral video LOL.

Hah! Well that's the idea. I'll figure it out if I have to.