Fuel control method for hand-carried engine-driven working machine

A fuel control method for a hand-carried engine-driven working machine having an assembly of an engine and a carburetor which are mounted on the hand-carried engine-driven working machine, the carburetor having a solenoid valve which is provided along a fuel line thereof to control a fuel flow rate in a working rotation speed range of the engine, the engine having a control unit provided therein to detect a rotation speed of the engine and control the solenoid valve, the fuel control method for the hand-carried engine-driven working machine comprising steps:

• performing a fuel flow rate adjusting process (F.F.R.A.P.) to adjust the fuel flow rate which is caused to vary based on a working environment by changing an opening of the solenoid valve after the engine is started and before actual work is performed;
• in the fuel flow rate adjusting process (F.F.R.A.P), with the engine operated under a definite load and at a definite throttle opening, and when a detected rotation speed, which is current rotation speed, enters a fuel flow rate adjusting rotation speed range (F.F.R.A.R.S.R.) that is set for adjusting the fuel flow rate within the working rotation speed range, adjusting the opening of the solenoid valve by feeding back the detected rotation speed so that the detected rotation speed becomes a target rotation speed which is predetermined as a rotation speed at which an air-fuel ratio expected in that state is obtained, and when the detected rotation speed stays within a fuel flow rate adjustment completion speed range (F.F.R.A.C.S.R.) which is predetermined within the fuel flow rate adjusting rotation speed range while the engine rotates a definite number of turns or for a definite period of time, determining the opening of the solenoid valve to be an adjustment completion opening (A.C.O.);
• and
• performing actual work at the obtained adjustment completion opening (A.C.O.) after completing the fuel flow rate adjusting process (F.F.R.A.P.).