TM  5-3895-360-13 Table  4-3.  Direct  Support  Troubleshooting  (Con’t). PROBLEM PROBABLE CAUSE TEST PROCEDURE/REMEDY ENGINE  (Con’t) 4. Engine  stalls  under  load. Fuel pump is faulty. Remove and disassemble carbure- tor  (see  paragraph  7-8).  Replace  fuel pump  as  necessary  (see  paragraph 7-8). 5. Engine is noisy or knocking. Bearings, piston rings, or cylinder Disassemble  engine  and  replace wall is worn. worn  parts  (see  paragraph  6-3). 6. Engine has poor acceleration. a. Fuel pump is faulty or carburetor a. Remove and disassemble car- is  dirty. buretor and inspect (see para- graph  7-8)  .Replace  fuel  pump  as necessary  (see  paragraph  7-8). b. Engine compression is low. b. Check engine compression (see paragraph 6-5). Replace piston rings if compression is low (see paragraph 6-3), DRIVE MECHANISM 7. No tamping  operation  while a.  Transmission  clutch  is  faulty. a.  Disassemble  the  transmission engine  running. clutch  (see  paragraph  10-3). b. Lower unit springs are faulty. b.  Disassemble  lower  unit  (see paragraph 13-3 or 13-4). 4-13/(4-14 Blank)