So I have a 2001 225 Optimax that has been giving me this issue for over year now & last dealer seems to mis-diagnose as a failed #6 direct injector last time in. Its starts & runs fine first thing out then after few minutes of running it shuts off. Cycle key & starts again then will shut of again as if hit kill switch. Last night though when going to restart I would get no warning buzzer when turning key on, Mercmonitor would not turn on, cranks but no start, no sound from relays & could not hear fuel pump cycle. Gauges associated with ignition switch work fine. Wait few minutes & would start but try get on plain, would mis-fire & shut off. It would do all the above things again & repeat until finally it would not fire at all or get buzzer on key on at all. Got towed in & checked fuses, there ok. Tried swapping trim & MPR relays, no luck. But once the ECU was cool to touch everything worked again & started fine. I read some were a failing ecu can cause the #6 direct injector not to work along with the Mercmonitor. So my best guess is the ECU is failing or maybe a issue with engine wire harness. Any ideas?
Eric
Eric