Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

2-Cycle TEC engine surging  and as it gets hotter the engine eventually dies after 10 minutes of running. I checked and cleaned everything.  Carb is spotless, changed ignition coil, exhaust ports & exhaust spotless, new sparkplug.  I did notice a bit of oily drops around the middle of the block. The compression seems to be ok when pulling the pull cord.

edgenet wrote:
Have you pulled the spark plug to check the colour?  If not, please do so and if you can, post a picture of it.  If no picture, please describe the coulour of the electrodes.

You say the carb is "spotless".  Does that mean you completely disassembled it, thoroughly cleaned every jet, orifice and gallery you could find?   If so, when you put the carb back on, did you make sure you put the little spring back on with the governor linkage?  Not sure how important that is, but it's pretty small and easy to misplace. 

The reason I ask is that your problems seems to be carburetor related.  I took the carb off of my 1997 Tecumseh two cycle engine (Craftsman single stage) and gave it a thorough cleaning just a couple weeks ago.  When doing so, I noticed that a Welch plug (aluminum disc half the size of a dime) had fallen from it position on the bottom of the carb and was resting on the float.  Obviously not doing it's job.  I replaced it and put the carb back together and the engine runs like a champ. 


   

Try running it with the gas cap off or at least very loose.  The vent in the gas cap may be plugged.  How much gas is in the tank?

fleetfoot wrote:
Very good point.  Often overlooked!

Normally, that's the first place I'd look. 

borat wrote:
I did not remove the carb. This is a mastercraft  blower and the carb can be seen from every angle. I poked and cleaned every opening in the carb. I will take another look if it does not work and if I can't see anything I  do have another  snowblower with a blown engine I may give that carb a try.

The carb has to be taken off and taken apart to be completely cleaned. 

If you don't want to do that, then least you should do is drain the fuel, take the cover off of the machine, put it over on it's bucket to get easy access to the carb, pull the float bowl off and clean the two small holes that go across the bolt with a piece of very thin wire.  Then see if you can feed the wire into the main jet.  Look through the big center hole in the float and you'll see the main jet.  Run  the wire in there as far as you can get it then blast it with WD-40 or spray carb cleaner.  If you have compressed air, try to blow through the main jet.  Be very careful with the float mechanism.  Handle it gently.  You do not want to mess up the float adjustment.  

Ok I swapped carb No Change with the other carb. I removed the top of the snowblower and watched as the engine ran  or should I say surging.  I noticed at the base of the muffler droplets of oil residue blowing out at the base of the muffler indicating a blown muffler gasket. I did not have a gasket so I used JB Weld as a sealer once it sets over-night I will give it a try. Any other thoughts.

If the engine is surging but continues to run, it sounds like there's a possibility your governor linkage might be off or mis-adjusted.  Are you able to take some pics of the carb from different angles to show us?  Might be something we can see that would cause your problem.  By the way, have you tried loosening the fuel cap to see if the engine will run better? 

All I can say this is crazy I will replace the spark plug one more time and if that does not work I will sell the sucker as a parts machine. There is a time to throw the towl-in and that time has come.

Did you try loosening the fuel cap and cleaning the carb?  You said you put on another carb but was it new or used?  If it was used, It may have been in need of a cleaning too.  The problem sounds fuel related.  Follow the fuel from the tank all the way to the carb.   These two cycle engines are very simple to work on and generally trouble free if fuel system is kept clean.

The cap's vent hole was clear and I did put a used carb but I cleaned it before installing. I did change the spark plug and I made sure it was gaped at .25 the engine is running much much better with the new plug. The plug I removed had a .35 gap I don't know how the old plug had such a large gap I always gap all plugs before installing new or used.

I believe the spark plug gap is supposed to be .030" so a gap of . 035 isn't all that wild and likely had no effect on how the engine ran.  Maybe the old plug was bad? 

Just a guess at this point,  The enige is running lean (surging).... If the carb is clean,  you may have a case leak or a bad seal around the crank...

   Start looking for bubbles (very small) around seals and gaskets while the engine is running... if you son't see any,  try spraying a mild dish soap solutionaround the seals and gaskets before the engine gets too hot...

The bubbles may appear small,  but you are only seeing bubbles when it makes bubbles.. 

Friiy

friiy wrote:
That was the 1st thing I tried to look for I could not find any leaks I thought I did find an oily gue spraying on the side of the block I traced that gue comming from the base of the muffeler.  I test the engine agine it seems to run nice. I am waiting for snow and then I can test it properly.