#1
IP: 12.31.214.68
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Carburetor Problem
I've recently replaced a seized Atomic 4 with one that is in good running condition. When I run the engine I've noticed a very small resedue of fuel developing on the air intake side of the carburetor. The scavenge tube on this particular carburetor has been removed and the opening has been plugged shut. I originally thought that the fuel leak might have been caused by the needle valve or the float sticking, so I took it apart and everything seems to be fine. So i replaced this carburetor with another. I was unable, due to space constraints and the inflexibility of the copper scavenge tube, to attach the scavenge tube at the flange. When I ran the engine, ALOT of fuel developed in the air intake, and actually started to drip under the engine. I am not sure why this is. Again I took apart the carburetor and the needle valve seems to be closing the orifice properly. Again, could this happen because of the scavenge tube not being attached? Unfortunately on this carburetor the idle screw is seized. But since it had been the original carburetor, I assume that it was set in the proper position. Any help with this problem would be great.
Cheers, Hank |
#2
IP: 208.157.149.190
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Hank,
Two thoughts: 1) The fuel collecting in the bottom of the carburetor throat is almost assuredly resulting from a defective or dirty float valve needle and seat. With no more than a new float valve costs, I think I'd replace it, given your recent history of problems, but I'd also install an inline polishing filter between the fuel pump and carburetor. To be absolutely certain that you'll be free of the problem, I recommend you take a bluntly pointed 3/16" wooden dowel rod and work it round and round hard against the seat in the float valve (even a new one) to be sure the edge of the hole in the seat is nicely polished and free of any sharp or irregular edge. 2) I recommend going back to the carburetor (or at least the upper housing of the carburetor) which does not have a seized idle mixture screw. There's no guarantee that you can rely on an idle mixture adjustment to hold for more than a season or so, let alone for a decade or more. When you reinstall a new scavenge tube, you'll have to reset the idle mixture at that time in any case. Don |
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