Merc 5.7 cut out

[lukecono]

Hello, while out for the past week boat ran great fired up every day idled, planed out no issues and very pleased. Reason being was that I just replaced my coil and thunderbolt IV 4'' box module after last one went bad. Its a 1984 formula three ls so 22-foot boat and went out and classic lake erie turned into 3-4 footers but on the beam so not bad. No issue. good vaca through 5 days until on the way back 2-3s downwind not a fun ride but got home after each way 38 miles. Idling down my channel glad i was almost back at 1200 rpms the engine cut out entirely, Blower remained on but entire dash and key had no power. Switches still worked. Inspected engine and coil, the module plugs wires looked for fluids, everything was normal. I wiggled one of my 3 wires behind my key ignition and got power back.

Question is what caused the engine to die like that and while under way? Are one of the 3 wires on the back side to the shift kill switch and somehow vibrated lose orrrrrr..? shut off and fired at dock again to make sure i was fine. Nothings out of the ordinary and I only have 3 wires to chose from. Thanks for the read.

 

[alldodge]

Question is what caused the engine to die like that and while under way? Are one of the 3 wires on the back side to the shift kill switch and somehow vibrated lose

Yes
The Red/Purple feeds power from the Bat
Purple feeds power to motor. Anything that disconnects power from Bat to motor will kill the motor. This is why the kill switch is in line with the purple wire.

Loose connection, key switch going bad, kill switch

 

[Grub54891]

Yeah If you wiggled wires and it re-started, thats where you have to look for the bad connection, or bad switch.

 

[lukecono]

I figured as it was pretty tell tale after the wiggle. The keys kind of looser than I would like in the key ignition switch so prolly just replace it all and force myself to redo the connections. THANK you both.