2006 Honda TRX680 Rincon Factory Service Manual, Page 562Get this manual
TROUBLESHOOTING 8Cylinder Compression Inspection Test cylinder compressionIs the compression low? YESValve clearance too small Valve stuck open Worn cylinder and piston rings Damaged cylinder head gasket Seized valve Improper valve timingGO TO STEP 9
9Fuel pump Inspection Inspect the fuel flowIs the fuel pump unit normal? NO YESFaulty fuel pump unit (page 6-36)TO STEP 10