TM  5-3895-360-13 Table  4-2.  Unit  Troubleshooting  (Con’t). PROBLEM PROBABLE CAUSE TEST PROCEDURE/REMEDY Engine  lacks  power  (Con’t). WARNING Compressed air used for cleaning or drying purposes, or for clearing restrictions,  should  never  exceed 30  psi  (207  kPa).  Wear  protective clothing (goggles/shield, gloves, etc.) and use caution to avoid lnju- ry to personnel. CAUTION Use care not to scratch or damage piston or cylinder walls when re- moving  carbon. g. Exhaust ports are clogged. g. Remove muffler (see paragraph 8-2)  and  rotate  engine  until  piston is at bottom of cylinder. Using scraper, remove carbon from ex- haust ports and clear with com- pressed  air.  Start  engine  (see paragraph 2-4) and run briefly to remove all carbon. Install muffler (see paragraph 8-2). h. Ignition is faulty. h. Check ignition wiring and coil and replace as necessary (see paragraph  9-2). 5.  Engine  stalls  under  load. a.  Carburetor  main  adjustment  is a.  Adjust  carburetor  (see  paragraph too  lean. 7-2). b. Fuel line is restricted. b.  Remove  fuel  line  (see  paragraph 7-6) and clear restriction, Re- place fuel line as necessary (see paragraph  7-6). 6. Engine misses. a. Sparkplug is defective or fouled. a. Replace spark plug (see para- graph 9-3). b. Spark plug gap is out of adjust- b. Clean spark plug points and set ment. gap at 0.040 in. (1.02 mm) 4-9