# Troubleshooting 3.5 HP Tecumseh (dies after 5 min., white smoke...)



## zuren1cs (Jan 9, 2007)

*Troubleshooting 3.5 HP Tecumseh (dies after 5-10 min., white smoke...)*

I've been doing some searches and not really finding what I think I need. I thought I would post this up while I continue to look.

What: 
3.5 HP Tecumseh on a Murray push mower (age unknown, at least 10 yrs. old)

Problem(s)/Description:
- Full tank of fresh gas, oil full (topped up with fresh)
- First start of season (3rd pull), blew white smoke but cleared and ran strong
- Ran for 5-10 min., blew a lot more white smoke, stalled, pull cord was seized (thought I seized the motor)
- Pushed it into the garage, let it sit for a week
- Revisited it yesterday, pull cord was free to spin, engine started on 3rd pull
- Ran strong again, RPMs became unstable when pushing back and forth (trimming under pine trees), RPMs would stabilize if I was gentle with back and forth motion
- After 10 min., small amount of white smoke blew out, engine stalled, could not restart, let it sit overnight
- Next morning (today) engine started on first easy pull with a very small amount of smoke, only wanted to see if it would start

I'm not small engine savvy, so I'm looking for guidance. I'm not sure if I have a fueling problem (indicated by the engine surging when pushing back and forth) or if it's an ignition problem. I plan to pull the plug today but I'm not convinced that is it or is contributing.

If anyone has any thoughts, I would love to hear them!

Thanks! :beer:


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## sluggermike (Apr 19, 2007)

The white smoke could be a problem with the oil seeping past the rings. From my limited experience the surging maybe a problem with the carb. Due to a dirty carb or the float sticking causing fuel starvation. Another thing to check is the governor.


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## oscaryu1 (Mar 25, 2007)

Isn't oil smoke supposed to be light blue or similar to that? It maybe surging like sluggermike said, adjust the carburetor, and make sure you didn't overfill the crankcase with oil.


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## zuren1cs (Jan 9, 2007)

Hopefully it is just an adjustment issue. Tonight, I did the following before trying again:

- changed the oil (oil smelled very gassy)
- pulled the plug (was heavily carboned and wet with fuel; cleaned it up and reinstalled)
- added fuel system cleaner to the gas tank

I started the mower and shot bursts of carb cleaner down the air intake (didn't want to take everything apart just yet). I let the mower run for 10+ minutes and it ran perfectly. I walked it across the lawn (running), began trimming and after 5 pushes, she died. I tried to restart and thick white smoke billowed out with each pull; she didn't restart. Came back to the garage and found the plug was wet again.

So it appears to be a fuel delivery issue. I don't have a manual for this mower, so I will be bumbling my way through this. I'll try cleaning the carb better and see what I can adjust as it seems to be getting too much fuel.


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## jsn_branum (Jun 9, 2007)

*this might help*

first thing i would do is do a valve job on it you can do it yourself or take it to your local small engine repair tech and also you might just be putting to much oil in and causeing it to leak around your tapet coverwhich will cause it to leak into the combustion chamber throught your valves try takeing some of it out and the stopping part might be caused by a bad coil so replace that if you can and also clean your carb with some carb cleanel and make sure u get in all the ports u can use the wire off a twist tie found on a loaf of bread 

hope this helps
jason :thumbsup:


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