Tecumseh ah817mb 2 stroke help.

#1
I had the engine running and it just died out after riding for a few. I tore the carb apart and cleaned it good with carb cleaner, put it back together the same way, made sure to count the needle turns and put them back the same turns. I've now noticed that when the fuel is turned on I have fuel coming out the crankshaft behind the clutch. I figure I have a bad crank seal. But is there a reason that gas pours out the crank shaft just by turning the fuel on. It doesn't seem right. Could I also have a carb issue. I'm not familiar with these engines at all. I just got a fox desert fox and this is the engine that was on it.
 
#2
Your carb isn't put back together right. Or if it is, you've got a chunk of debris stuck in the needle seat.

Time to take the carb apart again.
 
#3
The needle seat that is on the bottom of the carb under the cover, is that the one your speaking of? Do you think I also need the crankshaft seal? Do you know of anywhere to get parts, or parts that are interchangable?
 
#4
The needle seat seems to be clean of debris. I took the carb off and hooked the fuel line up and turned it on and it just pours out the orange rubber piece with a slit in it. Is this normal? I heard there needs to be gas oil mix in the crankcase for lubrication and it looks like it wold flow into the crank case. Could my problem be just the crankshaft seal and lack of compression giving me the inability to start the engine, I know some two strokes won't run if they loose there crankcase pressure.
 
#6
This orange rubber piece is where the fuel just rolls out, is that normal?
Not normal.
Carb looks to be in rough shape.
A complete rebuild is is needed. Rebuild kits can be found on Ebay or can be ordered from a small engine repair shop.
Faulty diaphragm is probable along with bad needle and seat.
Pop off pressure should be checked as well.
Also, crankcase should not fill with raw fuel. Fuel needs to be atomized (a vapor). That is what a properly functioning carburetor does.
 
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#7
I had this motor running when I first got it, and it seemed to gradually got ruffer running. I had sorta the same problem with a two stroke four wheeler, the crankshaft seals went out after it ran for awhile, I. Guessing they just got ate up after running it awhile cause they were dry and brittle from sitting for years. I think the same thing has happened to this motor.
 
#8
If I take off the side cover on this carb where the nipple for the fuel to go in is. I can see the inside of the Orange piece. And the fuel flows straight from the nipple through the Orange rubber.
 
#11
Now the next question though is if I fix this to where the fuel doesn't pour into the engine, will I still need to mess with any seal on the crankshaft? Doesn't seem right that any fluid should pass through where the crankshaft exits the engine block.
 
#12
Now the next question though is if I fix this to where the fuel doesn't pour into the engine, will I still need to mess with any seal on the crankshaft? Doesn't seem right that any fluid should pass through where the crankshaft exits the engine block.
I certainly would. Even if the seal isn't damaged, it's possible that the seal was popped out with the added pressure. Full of fuel, the compression in the lower end would be much higher as the piston descends.
 

markus

Well-Known Member
#18
Maybe these will help you out a little with part numbers to search:





This is from the 1980 engine specification book so it may vary from the 1972 a little:
 
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