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

I recently picked up a Airens ST1032 snowblower. It is in good shape but, when I bought it it was taken apart. The previous owner said it did not have any spark. I replaced the points and condenser and I also removed the cylinder head cover to check the condition of the piston and valves. They look good but i did notice a hair line crack in the cylinder head. (the part the spark plug screws into). It does not appear to go all the way through.

I am in the process of putting the motor back together, but with the cylinder cracked, I am also considering getting a new motor all together. How do i know if the head is trashed? It does seem to have a decent amount of compression, but it hard to tell, because i dont know what "normal" is for that motor?

It is a 10hp tecumseh HM100 motor

Any advice?

If the dent has increased the dimension of the float to cause it to get closer to the float bowl, it may very well be sticking in the closed position.   You  might want to move the float on it's axis to see how smoothly it moves with the float bowl off.  There is very little vertical movement but it should be smooth.  You might also want to make half of a simulated float bowl out of a tin can to use to see what kind of clearance the float has between it and the side of the simulated float bowl.  From what you're saying,  the engine seems to be experiencing fuel starvation.  Are you getting good consistent fuel flow to the carb?  You can test that by pulling the fuel line off at the carb and putting a container under it to allow the fuel to run  into it for a few seconds.  Take a good look at the fuel that comes out.  Look for water and dirt.    A picture of the float would be good to see.

You can get the Tecumseh factory number off the cowling and go to the link below for part numbers.  It should be stamped on top.

http://www.outdoordistributors.com/Tecumseh/Tecumsehpartslists.html

 

Do you have pullback causing the handle to pull out of your hands?  Timing.too advanced or gap too small causing an early fire?

 

Did you just break the starter cord with all the pulling?  A new cord can be strung pretty easily.

 

For the cost of a new tank and recoil you could get a motor.  There are plenty of glues around that will be ok with gas if the crack or hole is suitable for patching.  Patching a tank is a bother.  You can pickup a second hand tank

 

To see if it will run you can start it and keep punching the primer to get gas to it.  It seems like it still could have a block someplace.  The bowl is stepped.  The lower portion with the dimple goes away from the float hinge. 

I took the carb off of my other snowblower (st824) and swapped it, and it runs fine with no other adjustments. I went through the original one twice and have speant many hours playing with it, I think its time to get a new carb and be done with it. They seem to go for about $100.

The pull cord and recoil are ok, the handle slipped out of my hand once,and broke the tank.

dvdkea wrote:
Have you completely dis-assembled the carb down to it's basic components?  I.e. pulled and cleaned the jets, run wire and blown compressed air through the galleries, set float to spec, checked for manifold air leaks?  I've worked on a lot of carburetors for over 35 years and have never come across one yet that I couldn't fix.  Sure, might have taken a while to get it right but that was usually caused by being in too much of a hurry on the first or second go around.  

I did take the carb completly apart. Removed the jet, remover the chocke butterfly, and throttle butterfly, everything was apart, soaked it, and blew out all the passages, etc.

Something i did notice. The choke butterfly is bent. it appears to have been slightly beant so it would open and close. I did try to straighten it, got it flat, and the choke would not operate. Could the beant choke butterfly be causing this issue? 

If the engine is stalling because it's flooded, that could be attributed to the choke engaging after the engine is warmed up.  However, it it's a problem with fuel starvation, the choke will have no effect on that.  Next time you have it running and it stops, pull the spark plug to see if it's got any fuel on it.  If you don't see fuel, try to see if you can detect the smell of gasoline on it.  If you have evidence of gasoline, the engine is probably stalling from being flooded.  If not, you have fuel starvation.

I think it is starvation. I can keep it running with the choke off if i keep pushing on the primer. I have tried several adjustments on the main jet and also the air\fuel mixture with no real difference.

 

    If you can keep it running well for a while on primer then your gas line, float, needle are probably ok and no vacuum leak.  The float is working but the level could be off. 

    Your main jet needle should look like the one on that website i.e. the tip cut off.  7's and below had the pointed tip.  8's and above cut off.  You could try the nut and jet from the good working carb. 

    Some carbs are wicked fussy about the float level.  They are basically the same so I think it’s do to the way the machine sits.  Some ST824s sit level, some droop towards the handlebars and some a bit forward.  You seem starved so you could squeeze the float tab a hair to see if that helps.  If you can run for a short period (no prime) then it stops then let it sit for a while and it starts and runs for a short period again then it’s probably the float level.

    Are your carb linkages opening the throttle plate when you put it on full throttle?   You could open the choke butterfly and look in to be sure.

   1 turn on the idle and 1 ½ on the main jet are enough to get a carb to run so don’t bother with trying any adjustments until fine tuning after you locate whatever the problem is. 

 

   Seems like crud or a float adjustment. 

It is a new plastic float, the one that was originally in there was brass. The main needle jet does have the tip cut off, so it appears to be the correct one and is identical to the one that was in the carb before rebuild.

in this case, when adjusting the float level, i want to allow more fuel into the bowl, correct?

The carb linkages do open the throttle part way when the lever is at "fast" I was under the impression that this was normal, and the govenor would open the throttle more when needed. Is that correct?

I did install a inline fuel filter, could that be causing problems? but, then again, the carb from the st824 works fine with it.....

Trouts is probably on the right track.  I agree that it's probably a float setting issue.  I had a little two horse Evinrude engine that I couldn't get to run right for the longest time.  I was too lazy to pull the engine cowling off to take the carb out and tried to adjust the float with the carb on the engine.  Not a chance.  I had to take the engine apart and pull the carb to get the float setting right.  As he says, they can be very finicky.

The float and float needle work on the  principle of leverage.  When the float goes to the bottom of the bowl, causing demand for fuel, the float needle either opens on it's own with gravity or is pulled open via the float lever and a very small wire clip attached to the float needle and float lever.  The adjustment of the float is very critical and often only hav a millimeter or two float movement allowance.  If you have a fuel starvation issue, that means the float cannot move low enough and is not allowing sufficient movement of the float needle to permit sufficient fuel flow.  

I've had occasion when I couldn't dial in the float in and had to get creative.  So I carefully put the carb in a vice and rigged up a small bottle of water to the fuel hose going into the fuel inlet.  I then allowed water to flow down to the carb and controlled the float by hand to watch how much movement it needed to stop/allow the water flow.  This method is OK to get it close but water is heavier than gasoline and fine tuning might be necessary.  Focus on the float setting.  Sooner or later, you'll get it right.