Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 67Get this manual
IGNITION
DFI Troubleshooting Guide Symptom 1Engine cranks but won't start Cause 1.0 Lanyard stop switch in wrong position1.1 Weak battery or bad starter motor, battery voltage drops below volts while cranking (ECM cuts out below volts) (Fuel pump requires Volts)1.2 Low air pressure in rail (less than 70 psi at cranking Action Reset lanyard stop switchReplacecharge batteryInspect condition of starter motorCheck condition of battery terminals and cablesInspect air system for leaksInspect air filter for plugging (air pressure measured on port rail)Inspect air compressor reed valves if necessaryCheck that primer bulb is firmKey-on engine to verify that fuel pump runs for seconds and then turn offMeasure fuel pressure (valve on starboard rail)Fuel pressure should be 10 psi greater than the air pressureCheck fuel pressure from low pressure electric fuel pump (610 psi)Check for fuel leaksIf fuel pressure leaks down faster than air pressure, seals on fuel pump may be leakingCheck air system pressure, see 1.2Remove flywheel and inspect keyReplace fuseInspect engine harness and electrical componentsListen for relay to "click" when the key switch is turned onRemove fuel pump fuseUnplug all direct injector connectorsRemove spark plugs from each cylinderConnect spark plug leads to Spark Gap Tester 91-830230TCrank engine or use DDT output load test for each ignition coil and observe sparkIf no spark is present, replace appropriate ignition coilIf spark is present, replace spark plugs