Carburetor Metering Diaphragm The Shelf Spare

For anyone who works on small engines, the metering diaphragm is the one item kept on the shelf. It is not replaced when it breaks, it is replaced when it wears, and the 95-526-8 is one of the most common numbers in the family.

What does this diaphragm do? Inside the carburetor there is a diaphragm fuel pump, and the diaphragm is the heart that moves the fuel. As the engine turns, the diaphragm swells and contracts, drawing fuel from the tank into the carburetor while it meters the flow. When the diaphragm fails, the fuel no longer runs steady, and the machine starts now and not now, loses power, and idles unevenly.

Why is this number so common? The 95-526-8 is a metering diaphragm shared across small engines, mowers and chainsaws among them. Its family, the 95-526, 95-526-9 and 95-526-9-8, interchange, so a large stretch of machines all use this shape of diaphragm. It wearing out is only a matter of time, and every engine will come to need one.

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.