View Full Version : String Trimmer Carb Issue
08-08-2010, 11:52 PM
My 1982 Green Machine (3000SS) runs great when level and when turned to the right but when turned to the left and upside down it loses power (running rich?). Return to the upright position and power returns. I have installed a carb kit and still the same performance. Any ideas?
08-09-2010, 07:50 AM
Try turning the unit upside down. If it dies smoking alot, you likely have some accumulated fuel and oil in the bottom of the crank case. When you tilt it, the unit may be picking up some of that excess fuel.
I never did notice this problem much with hand held equipment but the problem was prevalent in the Toro two stroke snow blowers that had set with fuel from one season to the next. To clear that fuel, the engine had to be tilted so that fuel/oil could be picked up and eliminated.
Just in case you may be misreading the problem, check the condition and position of the fuel pickup in the fuel tank. Is there a possibility that the fuel line has hardened enough that the filter will no longer keep itself in the fuel.
I'm not saying that it isn't carb related but 2 stroke carbs are designed for operation in multiple positions.
08-09-2010, 09:43 PM
The fuel filter is free to move and the hose flexible. The fuel being trapped in the crankcase is possible. I ran it about 20 minutes vertically and the problem still exists - do you think I need to run it longer to clear the crankcase?
08-09-2010, 10:06 PM
Running engine upside down for just a couple of minutes should clear any fuel/oil in the crankcase. Most of these types of scenarios are fuel related but at present I can't come up with any relevant solutions fro a rich condition. Had it been a lean situation, there are other possibilities.
Is this problem occuring regardless of fuel level in tank?
08-10-2010, 12:45 AM
Tank is almost full. I will try it with less in the tank. As I think about it, tilted to the left with a full tank might increase the fuel pump suction pressure and overcome the spring pressure in the needle/seat causing the rich condition. Far fetched idea but do you think it is a possibility?
08-10-2010, 01:40 AM
A diaphram carburetor is just a stupid float carburetor. The float in a diaphram carburetor is adjusted by bending the arm that controls the needle and seat. You need to adjust the end of the arm that makes contact with the diaphragm a little closer to the carb body. Adjusting this lever changes the amount of fuel over the diaphragm just like adjusting a float in a float carb will control the amount of fuel in the float bowl. You currently have to much fuel above the diaphragm which forces it to run rich when you turn it upside down. The carb is made by Tie Kie in japan and they used to furnish a gage to set it. I have no idea where you could find one nowday's so its a trial and error thing until it is set right. Hope this helps.
08-10-2010, 09:19 AM
There is a possibility that the metering lever is set to high, but that doesn't make any sense if it was operating the same way before the carb rebuild--unless the carb had been rebuilt before with the same problem.
08-10-2010, 08:51 PM
Or the gasket or diaphragm were a different thickness in the new carb kit.
08-10-2010, 09:22 PM
Adjusted the needle to reduce the volume of gas and the problem is solved. I wonder if it will last another 30 years.
Thanks for your help and ideas.
08-10-2010, 11:43 PM
Brings back lots of memories. Worked for them for 18 years. Keep feeding it good gas and quality oil and it just may last another 30 years.
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