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Discussion Starter #1 (Edited)
Hello

I have a 06 vintage snapper Le19 I picked up used with the Tecumseh 3hp 2 stroke.
I never saw it run before I tore into it

Currently it will start and run without any hiccups when I use the electric starter, though it takes 2-3 seconds to catch. Once it is running, it sounds and runs great even at WOT.
My issue is pull starting. I?ve verified the arms come out and it does turn over but will not start no matter how many pulls.

So far I?ve replaced:
Spark plug
Coil
Entire carb (from local shop)
Fresh gas mix. (Drained tank)
Fuel line and filter

Any advice would be appreciated.
 

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I agree with those two possibilities
1) bad compression
2) no primer so no gas to give it a good chance of starting.... however the starter motor is priming it for you

Here's another two possibilities ...
3) Primer button is split and not actually doing anything. can you hear gas squirting when you prime? That tests the button AND the primer hose.
4) choke not working because lever is not connected
When you've had it running a while. if you shut it down and then immediately pull the rope... does it fire right up?
Warm engines don't need the choke but a cold engine does

$0.02

By the way.. that's a lot of things you changed.
You've totally switched out the entire fuel system (except the gas tank and primer button and primer hose)
You've totally switched out the entire ignition system
That only leaves one thing... compression
Pity if it was that all along.. do you have compression tester? How are you deciding if the compression is or isn't OK?
 

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Discussion Starter #4
I agree with those two possibilities
1) bad compression
2) no primer so no gas to give it a good chance of starting.... however the starter motor is priming it for you

Here's another two possibilities ...
3) Primer button is split and not actually doing anything. can you hear gas squirting when you prime? That tests the button AND the primer hose.
4) choke not working because lever is not connected
When you've had it running a while. if you shut it down and then immediately pull the rope... does it fire right up?
Warm engines don't need the choke but a cold engine does

$0.02

By the way.. that's a lot of things you changed.
You've totally switched out the entire fuel system (except the gas tank and primer button and primer hose)
You've totally switched out the entire ignition system
That only leaves one thing... compression
Pity if it was that all along.. do you have compression tester? How are you deciding if the compression is or isn't OK?

Stuart,

I can verify the choke moves when the lever is moved.
I removed the primer and can feel the air coming out when I push it. I will replace and see if it changes.

Immediately after it runs, I can shut it down, wait 5 seconds and it will start by pulling. Wait any longer than that and it will not.

I also suspect low compression but deep down had been hoping that was not it, as it seemed to run great when turned over by the starter. I have now acquired a tester and will know tomorrow what the compression is. Any idea what it should be?

Also I had theorized that the primer was not moving fuel and that the starter is pulling the fuel to start it. Still trying to locate one local.

Thanks for the help!
 

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Stuart,
I can verify the choke moves when the lever is moved.
I removed the primer and can feel the air coming out when I push it. I will replace and see if it changes.
Immediately after it runs, I can shut it down, wait 5 seconds and it will start by pulling. Wait any longer than that and it will not.
I also suspect low compression but deep down had been hoping that was not it, as it seemed to run great when turned over by the starter. I have now acquired a tester and will know tomorrow what the compression is. Any idea what it should be?
Also I had theorized that the primer was not moving fuel and that the starter is pulling the fuel to start it. Still trying to locate one local.
Thanks for the help!
If you can feel the air squirt.. you are just throwing money at it if you change the primer bulb IMO. Only change what you KNOW to be bad whenever possible. I think you've already changed way more than I would have done (unless I HAD to).
The fact that you CAN start it up soon after a shutdown is a clue but I can't get my head around why things change after only 5 seconds. If you'd said 60 minutes my earlier suggestion may have helped... that would have let things cool down.

I am wondering if you set that new ignition coil up properly with a business card for the gap and whether it's slipped a bit. But that's just me clutching at straws.
That doesn't explain the 5 second phenomenon though.
I'm sorry I don't know the specific answer for the compression but for 2 cycle engines you won't have a decompression system built into it. That can mess folks up with 4 cycle engines who THINK they have low compression because the pull rope is too easy to pull... turns out that's by design.... but not in your case. That's usually for bigger engines to drop the compression to make it easier to get some fly-wheel momentum going with the pull rope.


As a rule of thumb.. if I get 90lbs I can usually start the engine... if it drops to (say) 60 you probably have a problem. There ARE technical repair manuals out there for engines that tell the repair guys what values are suspicious in the trouble-shooting section. Did you try googling for the "Service Manual" for your engine? Or maybe someone here will post a link for you. I'm a bit busy clearing leaves but might be able to help later if I don't forget or someone gets you the answer quicker.
 

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Just had another thought... governor controls and linkages etc

If they are not right and you got the linkage in the wrong hole it will mess up the way the linkages reset the throttle plates etc etc.
Are there multiple holes to pick from on the carb? Are you sure you know you used the right one? Or maybe there's just one hole and you can't get it wrong. I'm not looking at any pictures or schematics here.... just thinking aloud ;-)
That doesn't explain the 5 second phenomenon though.
 

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I've got other thoughts too depending on if you've INTRODUCED a problem by changing so much stuff.
For example, if the gaskets are messed up or missing when you replaced that carburetor or the bolts are loose you could have an air leak.
That would mess things up with the mixture and you'd be running too lean. A big clue there is if you can't turn the choke off and keep it running (but you didn't mention that symptom).
There are ways to check for that by squirting Carb Cleaner around the gaskets when the engine is running and see if it affects how it runs.
If there is a gap there.. the carb cleaner will get in (along with the air) and the engine will change how it runs for a second or two.
That doesn't explain the 5 second phenomenon though.

back to the leaves
 
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