Is there something about Ariens Tecumsehs...I'm still having a similar issue with my old Ariens snowblower....hope someone has an idea...

Loosen the gas cap,see if it will stay running.Could have a vacuum in the gas tank causing it not to run.Also recheck your float in the carb. to see if it has gas inside the float.Put the float up to your ear and see if you hear any gas inside,if so replace.Hope this helps.

Jerry

"The engine starts and as soon as I let go of the starter handle it dies" There's your problem. I think the starter handle relay is stuck in "hold on" mode! :) But seriously a little more history could be helpful. Had it set for a while? Varnish or corrosion present? Be sure the float level is set properly, bowl seal replaced and double check that the throttle shaft is working freely for starters.

Here is a link that might be useful: Tec 4cycle manual pdf

I put another carb on from another Tecumseh engine, same symptons.
Priming it continuously does not help.

Could this be something to do with the ignition module, causing a weak spark, that disappears after the start handle is released?

I can see no points or condenser, just a coil and a second smaller coil off to the side.

What is this "start handle"?

Again, more info would be helpful. You put a carb on from a known good, similar engine or? Perchance is the throttle link installed in such a way that the throttle plate is not open. A fuel line that is deteriorating /contaminated will create issues w/ the second carb as well. Sure, you could have a module that is dying- but not a likely cause. If you have a coil outside the flywheel rather than underneath, it has no points. Try it with the small wire from the coil unhooked to be sure the switch / kill wire isn't intermittently grounding. Take a can of carb spray and see if you can keep it running by intermittently spraying into the carb venturi. You really shouldn't keep the history of this engine to yourself. It isn't helping. Heck, maybe you have a valve not closing or a blown head gasket... More info.

I have an old Ariens 5 hp self propelled battery start that I am trying to revive. Engine is Tecumseh TVS120. Non adjustable carb.
The engine starts and as soon as I let go of the starter handle it dies.
The carb and tank has been cleaned.
Fresh gas.
New vacuum line for prime.
New fuel line between tank and carb.
All the holes in the carb are open, clean, even the little ones in the float plug.
Compression is 70 psig .
No cap on tank for the purpose of testing.
No fluid in the float.
No varnish or corrosion present as everything has been cleaned with carb cleaner.
Float level is set properly.
Throttle shaft is working freely.

There is a coil underneath the flywheel, with a smaller coil / condensator sitting right next to it. I don't see any points.

I have not yet replaced the rubber bowl gasket, don't believe that would kill the engine after 2 seconds.

No secrets.

At one time I was able to keep it running with quick start.

The alternate carb I tried was from a Sears engine also 5 hp, also Tecumseh. Symptons didn't change

The throttle plate is closed just sitting there but when the engine is cranked I see the plate on top move open.

I still don't know what a "starter handle" is.

Somewhat better info. With complete engine #s parts look up MAY tell us for sure what all your parts are. I encourage you to get into the service manual. I would still like to know a few other things.

"No varnish or corrosion present as everything has been cleaned with carb cleaner." Well, corrosion doesn't come out w/ standard carb cleaner. The thing to know here is that Tecumseh carbs are not clean up friendly. Water damage is irreversible.

"There is a coil underneath the flywheel, with a smaller coil / condensator sitting right next to it. I don't see any points." The only coil that I'm familiar with that is under the flywheel would be the ignition coil. The breakers are under the cover that goes over the crank. Electronic ignition on these are external of the flywheel and no condenser is used. A smaller coil should be the charge coil for the battery. Maybe a light file on the points would help, tho the point and condenser are cheap enough. It should ground when the breakers close. You can simply unhook the condenser for a test. It would probably be old enough not to have the "T" style flywheel key? Which by the way are available in 2 versions that don't interchange.

"I have not yet replaced the rubber bowl gasket, don't believe that would kill the engine after 2 seconds." It's like this: A Tecumseh engine will run with an improper bowl seal, yes. Not always well as it changes the environmental rules set by the guy who designed it. A pitted bowl or a deteriorated seal will allow it to lose its e.i. It won't prime properly however, so if you had gotten it started by using carb spray- it would continue to run.

"At one time I was able to keep it running with quick start." I do suggest carb spray as a tamer version of quick start. How long did you have it running for? And how long ago was this? Has the machine sat? These are important questions. Look at it this way. If it starts and runs as long as you are directly providing the "fuel"- then you know you have spark and compression.

"The alternate carb I tried was from a Sears engine also 5 hp, also Tecumseh. Symptons didn't change." And this engine runs well currently?

"The throttle plate is closed just sitting there but when the engine is cranked I see the plate on top move open."
This engine will want to start when the throttle plate is open only. I assume this thing has a throttle cable. Maybe do a test and prop the throttle shaft 1/4 or so open and try starting.

My responses are getting as long as Mownies- yikes!

LOL, I scrolled up a little.....I thought it was mownie.

Sounds like an issue with this starter switch(handle).

Maybe it's the handle at the end of the
starter rope?

If it's a lawnmower, it's normal to stop when you let go of the starter handle. If it's a snowblower with a mitten handle, would it keep running if you held on to the handle?

When he sez: Starter handle---does he mean the bail handle that must be held back so it releases the flywheel brake? Letting go of that starting bail handle would surely make the engine stop!
And, if he has messed with the points, and other stuff under the flywheel--he'd be better off to install a similar B&S engine, one that an electronic ignition kit could be installed on it! From my experience with Tec points, they are headache number one if they go bad!

Since the email isn't/wasn't working on this site, he probably doesn't even know we're talking about him or responding to his question.