2003 8.1 EFI dies

[bobterisch]

Hello everyone,
2003 8.1 inboard, starts fine idles nice then ramdomly dies. Sometime it runs for 1 minute sometime 10, sometimes it runs all day. When it dies and we try to restart sometimes it starts right up other times it is completely dead(no buzzer). Seems to be worse in the cold. When it is running we noticed that the tach randomly jumps all over the dial.
Thanks for your help,
Bob

 

[alldodge]

I think your loosing a ground or 12V power. Could be connections, key switch, relay or PCM

 

[Fun Times]

One other thought of many could be since the tachometer jumps around is that you may want to inspect the wiring going to the Crankshaft sensor as maybe it became compromised during say a water pump impeller service as they are kind of in the same general area enough that something may have accidently touched the sensor and/or wiring while working....Item # 12, http://www.mercruiserparts.com/bam/s...1676/11838/110

 

[bobterisch]

Thanks for the replies. Will try your suggestions and follow up.

 

[bobterisch]

Was ignition switch. Thank you for your help!