Briggs and Stratton Diaphragm Instructions


The first set of instructions is for Briggs and Stratton Quattro, Classic, Sprint, and unnamed 3.0-4.0 h.p. vertical shaft engines.

  • 1.) Remove the air filter.

  • 2.) Now remove the 1/2" and 7/16" bolts holding the carburetor to the block and control bracket.

  • 3.) Pull the carburetor and tank assembly toward you to remove from the intake manifold.

  • 4.) Rotate the assembly toward the engine and twist to the right to free the governor linkage from the carburetor.

  • 5.) If the gas is contaminated, old, or has debris in it, this would be the time to dispose of the fuel properly.

  • 6.) Remove the 4 or 5 screws holding the carburetor to the tank. NOTE:**SOME MODEL 11 (11xxxx) ENGINES WILL HAVE A SCREW INSIDE THE AIR HORN, UNDER THE CHOKE PLATE. BE SURE TO REMOVE THIS BEFORE REMOVING THE CARBURETOR FROM THE TANK.**

  • 7.) Slowly remove the carburetor from the tank and make a note of where the springs came from. On automatic choke carburetors, remove the cover with a 1/4" nut runner or wrench and unhook the rod from the choke. The diaphragm should now fall out.

  • 8.) Check for fuel in the chamber where the long spring goes in (automatic choke engines.) If there is fuel in that chamber, the tank must be trued. Take the tank to an Authorized Briggs and Stratton dealer and have them true the tank or order a repair kit.

  • 9.) Take the Model and Type and Code number from the engine shroud and go to a Briggs and Stratton dealer and get the correct diaphragm. If you have a primer on the carburetor, the P/N for the diaphragm is 495770.

  • 10.) On automatic choke carburetors, you must install the copper spring to the bottom of the diaphragm. Follow the instructions included in the box. Now hook up the copper link to the choke plate and reinstall the cover. Make sure you have the spring(s) in the correct place and invert the fuel tank and place carburetor to the tank and set the assmebly on the bench. Install the scews and turn 1 time.

  • 11.) Put a screw driver in the air horn, to hold the choke open past half-way and gently shake the carburetor to set the choke spring. Tighten down the carburetor to the tank in a staggered sequence.

  • 12.) On primer equiped engines, put the diaphragm on the tank and a new gasket on top of the diaphragm. Lower carburetor on top of the gasket and diaphragm and install and tighten the 5 screws.

  • 13.) Reinstall the carburetor and tank assembly to the engine is reverse order of taking it off. Install the two bolts and air cleaner.
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