Just something to look into.... I dropped my ActionCraft in Mosquito Lagoon on Tuesday around 6:30AM, the wind was still and there wasn't a ripple on the lagoon. I fired the Optimax up, and proceeded to get the Garmin ready. Less than a minute into warmup, I get the alarm sounding, and the SmartCraft displaying "Check Engine, Injector Fault." I shut the motor off, waiting a few minutes, and refired, in some slim hope there was some sort of glitch. No dice, alarm immediately started sounding again.
I pulled the boat out of the water and popped the cowling, hoping something would be gleaming, like a loose connector on one of the injectors - no dice as well, all were snug, or so I thought.. I stopped by one of our local Mercury Race Builders who happens to have a DDT, and started checking each injector, expecting to drop at least $450 on a new direct injector. We made it through all 6 fuel, and 5 of the direct injectors with no faults and good sounds, when injector number 6 starting sputtering and triggered the alarm again. Injector is toast, right? No, we swapped direct injector 4 for injector 6, and all of sudden, the "new" number 4 starts working and sounds great. The "new" number 6 won't even fire now... I recently had a new PCM put on the motor, and I immediately started thinking the PCM has failed, but I could hear the a relay coming on when ever we started the injector 6 test, even though no injector fired. I went back to basics first, checking the continuity of the lead from the PCM to the injector, and had continuity. I checked for a dead short from the PCM lead to the engine ground, and had nothing. I checked the injector harness ground to the engine and had continuity.
Ruling out a short, a PCM failure, or a bad injector, I focused my attention on the injector electrical connector. We restarted the injector test on number 6, and during the test, I jiggled the connector, and boom, injector started firing. I held the connector in the position that made it work, and the injector continued to fire perfectly during the test with no alarms. There was no corrosion or other issues visible.
I went ahead and removed the end connector from the harness and directly attached the leads to the injector (insulated with electrical tape of course) simply to flush out the motor. I had to use a pair of needle nose to tighten both of the female connector ends (not the injector male ends) to get them to be tight, so it was clear the connector was loose. May be wishful thinking, but I swear the motor is idling smoother than before. I have a new connector on order to install this weekend.
Needless to say, check all of your injector harnesses and make sure they are good and tight. If you get an injector fault alarm, check your connectors first instead of immediately assuming you have a bad injector and ruining a perfect day of fishing....