Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 69Get this manual
IGNITION
DFI Troubleshooting Guide (continued) Symptom 3Engine idle is rough Cause 3.1 Low air pressure in rail (less than 79 psi while running) 3.2 Fouled spark plug See 1.2 Replace spark plug: If carbon bridges electrode gap or if it is completely black If it is not firing and is wet with fuelNote: If spark plug is grey or completely black with aluminum specs, this indicates scuffed pistonRefer to specifications for ohm testRefer to specifications for ohm testRefer to specifications for ohm testRemove flywheel and inspect keyMeasure fuel pressureRemove and inspect diaphragms (a special tool is required for assembly)Check for fuel entering induction manifold or air compressor inletFuel pump diaphragm leaking and or Vapor Separator flooding overInspect tracker valve for proper assemblyCheck throttle cablecam roller adjustmentSee 3.2 See 1.2 Check throttle cam setup on induction manifoldInspect linkage and rollerIf throttle plate stop screws have been tampered with, contact Mercury Marine Service Department for correct adjustment proceduresSee 3.5 See 2.4 See 3.2 See See 1.2 See 2.4 Action