Poulan 1994-04 User Manual - Page 21

- Loss of cutting power which cannot be corrected by cleaning the air filter. See "High Speed Mixture Adjustment." - Engine does not return to idle from full speed within 2 seconds. See "Deceleration Check." - Engine will not run. See "Trouble Shooting Chart." Then, if carburetor requires adjustment, begin with "Basic Carburetor Settings." A WARNING The trimmer line will be spinning during most of this procedure. Wear your protective equipment and observe all safety instructions. 2. BASIC CARBURETOR SETTINGS NOM,: In most cases, your engine can be made to run properly with minor carburetor adjustments. Refer to "Trouble Shooting Suggestions" in the left column for the condition you are experiencing and follow the instructions. The basic carburetor settings are provided below. a. Turn low speed mixture screw and high speed mixture screw (Figure 30) clockwise until they stop. Do not turn screws until they are tight as damage to needle seats can occur b. Turn the low speed mixture and high speed mixture screws between three-quarters and one full turn counterclockwise. 3. ADJUSTING PROCEDURE a. PREPARATION 1. Use a fresh fuel mix. See Fueling section. 2. Make sure the line extends to the length allowed by the line limiter to provide correct load on engine. 3. Start the engine. Cut grass for 3 minutes to warm engine. The engine must be at operating temperature before carburetor adjustments can be performed correctly. b. IDLE SPEED ADJUSTMENT 1. Allow engine to idle. 2. Adjust idle speed screw (Figure 30 ) until the engine continues to run without stalling and without the trimmer head moving. - Turn screw clockwise to increase engine speed if the engine stalls or dies. - Turn screw counterclockwise to slow engine down and/or to keep trimmer head from turning. 3. Follow instructions in "Acceleration Check" and "Deceleration Check." 4. No further adjustments are necessary if trimmer head does not turn at idle speed and performance issatisfactory. A WARNING Recheck idle speed after each adjustment. The trimmer head must not turn at idle speed to avoid serious injury to the operator and others. c. ACCELERATION CHECK 1. Allow engine to idle. 2. Squeeze trigger fully a.) If performance is satisfactory, proceed to "d. Deceleration Check." b.) If the engine does not accelerate smoothly, turn the low speed mixture screw (Figure 30 ) counterclockwise a small amount (no more than the width of the slot in the adjusting screw). 3. Repeat step "2." until smooth acceleration is obtained. NOTE: It may be necessary to repeat "Idle Speed Adjustment" through "Acceleration Check," to obtain correct adjustments. 4. Follow instructions in "Deceleration Check." d. DECELERATION CHECK 1. Allow engine to idle, then squeeze throttle trigger fully 2. Allow engine to run at full speed for about 1 second. 3. Release the throttle trigger to the idle position and listen to the deceleration of the engine. It must return to idle smoothly and within 1 to 2 seconds. a.) If performance is satisfactory, proceed to step "4." b.) If the engine slowly or erratically returns to idle or idles erratically, repeat "Idle Speed Adjustment" or continue through "Low Speed Mixture" and "High Speed Mixture Adjustments" to obtain proper deceleration. 4. Recheck idle speed. High Speed rScerwt nemn N44 e Low Speed Adjustment Screw "Nose Cone" Air Filter Cover Screws Idle Speed Adjustment Screw vka Figure 30 e. LOW SPEED MIXTURE ADJUSTMENT I. Allow engine to idle. 2. Turn the low speed mixture screw (Figure 30 ) slowly clockwise until the speed starts to drop. Note this position. 3. Turn the low speed mixture screw counterclocicwise until speed increases and then starts to drop again. Note this position. 4. Set the low speed mixture screw at the midpoint between the two positions. 5. Follow instructions in "Acceleration Check" and "Deceleration Check," f. HIGH SPEED MIXTURE ADJUSTMENT CAUTION: I Do not operate engine at full throttle for prolonged periods while making high speed adjustments as damage to the engine can occur. 1. Support tube so trimmer line is off ground and will not make contact with any object. 2. Allow engine to idle, then squeeze throttle trigger fully. NOTE: Perform steps "3." through "5." at full throttle. 3. Turn the high speed mixture screw (Figure 30 ) very slowly clockwise until engine speed is reduced. 4. Turn high speed mixture screw very slowly counterclockwise. Stop when the engine begins to run roughly 5. Turn screw slowly the minimum amount clockwise until the engine runs smoothly 6. Follow instructions in "Acceleration Check" and "Deceleration Check". I CATITION: I If the engine does not operate according to these instructions after repeating the adjusting steps, do not use the tool. Take it to your Authorized Service Dealer. - 21 -