Metering Diaphragm Why One Part Has Many Numbers

When you see 95-526 followed by 8, 9 or 9-8, do not assume they are a pile of different parts. They are basically the same diaphragm, and the 95-526-9-8 is one member of the family.

Why does one diaphragm carry so many numbers? A carburetor metering diaphragm gets revised over the years, and the number changes with each revision, while the shape and the job stay much the same, so the end result is that they interchange. The 95-526, 95-526-8, 95-526-9 and 95-526-9-8 are all in this family. When you buy, look at which number the old diaphragm is marked with, and take one from the same family.

What does the diaphragm do? Inside the carburetor there is a metering diaphragm, the diaphragm fuel pump, and the diaphragm is what moves the fuel. As the engine runs, the diaphragm swells and contracts, drawing fuel from the tank into the carburetor and metering the amount. When the diaphragm fails, the fuel stops coming, and the engine starts now and not now, with the power dropping.

What is the part like? The diaphragm is black rubber, with a rectangular flange, a notch at the top for alignment, and six screw holes around it, two on the upper lugs and four at the corners. In the center is a recessed rubber dome, and on it a metal plate with five round holes and a small central metal pin. The metal plate and the rubber work together as the metering assembly.

How to replace it? Take the old diaphragm off, compare it with the new one and confirm the way up, metal plate forward, line the six holes up with the pump body, and press the diaphragm flat so it does not wrinkle. Tighten the fasteners evenly, then give the engine a start and check that the fuel runs steady.