At what point would you delete the oil injection and start manual mixing your oil. I have a 2004 Mercury 60 HP on my tin boat. that everything is working fine, but am starting to be cautious of it just cause of the age and not knowing a lot of the history, besides it wasn't run for almost 15 years.

Way more cases of people forgetting to premix there there are of oil injection systems going bad. Leave it alone.

Doesn't your motor have a guard mode that kicks in if there's an issue with the motor? I had an oil pump start to fail on an Evinrude years ago, and the system saved itself by going into that mode (limiting performance). It was obvious something was wrong, so I limped in carefully and had it repaired with no lasting effect. I agree with tmd that more pre-mix motors probably get fried from owners forgetting or calculating incorrectly than injection system failures.

I’ve blown 2 motors because the alarm didn’t work. They were very Oder motors and I had the VRO pump unhooked after both rebuilds. My grandad always warmed me to mix my own oil from the get go.

I am wondering if the horn wasn't functional. Did you get the horn-test beep when you started the engine on the day of failure? The horn gets corroded and can fail, and some people never think ahead on what might result when they don't pay attention and notice that the horn-test has stopped working.

Premixing is mighty simple, cant imagine how much of a [censored] one would have to be to omit adding oil to their fuel. Been premixing for 50 years. Never once forgot.

I pre mix.
Just don’t ever loan it out.