Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 64Get this manual
IGNITION
Troubleshooting Without Digital Diagnostic Terminal
Troubleshooting without the DDT is limited to checking resistance on some of the sensorsTypical failures usually do not involve the ECMConnectors, set-up, and mechanical wear are most likely at fault Verify spark plug wires are securely installed (pushed in) into the coil towerThe engine may not run or may not run above idle with the wrong spark plugs installedSwap ignition coils to see if the problem follows the coil or stays with the particular cylinder
NOTE: ECMs are capable of performing cylinder misfire test to isolate problem cylindersOnce suspect cylinder is located, an output load test on the ignition coil, fuel injector and direct injector may be initiated through use of the DDT Any sensor or connection can be disconnected and reconnected while the engine is operating without damaging the ECMDisconnecting the crank position sensor will stop the engine