Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 70Get this manual
IGNITION
DFI Troubleshooting Guide (continued) Symptom 7Speed Reduction (RPM reduced or limited to 3000) Cause 7.1 Low battery voltage ECM requires volts minimum Fuel Pump requires volts 7.2 Overheat condition (engine andor air compressor) 7.3 Oil pump electrical failure 7.4 TPS failure If one (1) TPS fails rpm is reduced to 3,000If both TPSs fail, rpm is reduced to idle 8Engine RPM reduced to idle only 9Loss of spark on cylinder 8.1 Both TPSs failed 8.2 Battery voltage below 9.5 volts 9.1 Loose wire or pin in connectors between ECM and coil primary9.2 Faulty ignition coil9.3 Faulty spark plug9.4 Faulty spark plug wire Note: Due to the long spark duration of this ignition system, the DDT may indicate the incorrect cylinder as having an ignition faultExample: If the DDT indicates an ignition fault on cylinder #4, the problem may be on the prior cylinder in the firing order I.Ecylinder number #3Action Check battery andor alternatorCheck electrical connectionsCheck water pump impellercooling systemCheck electrical connectionCheck electrical connections