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How to Adjust a Briggs & Stratton Pulsa Jet Carburetor

The Briggs and Stratton Pulsa Jet carburetor regulates fuel flow on the aluminum series of engines. The most common application of this carburetor is for small horsepower lawn mowers and rototillers. The Pulsa Jet carburetor resides above the on-board gasoline tank. Fuel is drawn up into the device through two fuel suction lines. A single needle valve resides near the rear of the carburetor unit, that faces the push handles of the mower or rototiller. The needle valve has a slot-type screw head.

Close the needle valve with the screwdriver in a clockwise direction.

Open the needle valve 1 1/2 turns in a counter-clockwise direction. This setting allows the engine to be started and warmed to operation temperature. Keep the air filter in place for correct adjustment.

Start the engine according to the manufacturer's instructions for the device. Accelerate the engine to operational speed.

Turn the needle valve in a clockwise direction, closing it, until the engine begins to lose speed. Slowly back the needle valve out, counter-clockwise direction, until the engine smooths out.

Test the engine under a full-load condition. Mow grass with the lawn mower or cultivate soil with the rototiller. Turn the needle valve slightly in a counter-clockwise direction if the engine loses speed while under full-load conditions. It may take several minor adjustments to the needle valve in order to get the best performance from the engine.

Adjust A Walbro Carburetor

Walbro carburetors are almost standard on most all two-cycle engines. Adjustment of the carburetor may have to be performed on a periodic basis and most definitely after the simple device is rebuilt. Identify the two-fuel adjustment screws on the side of the metal carburetor. The “lo” fuel screw is for when the engine is idling. Start the two-cycle engine. Allow the engine to return to an idle operation by releasing the throttle. At idle the engine should be running smoothly. Quickly depress the throttle again.


Use only fresh gasoline in the engine when performing the above adjustment as old gasoline will cause the engine to operate erratically. If the device fails to adjust properly after following the above steps, the two fuel suction lines may be clogged. There are small screens in the ends of both plastic tubes. The carburetor must be removed from the fuel tank and the lines or screens cleaned.

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