2004 Mercruiser 4.3l (Gen+) #0W011342 stall when warmed up

[PlayDate]

The root cause was a failing oil pressure safety switch (<1yr old) that intermittently/occasionally worked correctly. The part was replaced late last year with a genuine Mercury part from the local dealer. Confirmed by shorting the connector to bypass the switch and energize the fuel pump with a Dupont connector male-male cable (paper clip would've worked as well).

When the starter cranks the engine, the starter harness provides power to the fuel pump to bridge the gap until the engine makes pressure to close the switch. This is enough to supply the carb with a small amount of fuel to run. Once the carburetor is out of fuel, the engine shuts down.

The ~15s duration should've been a clue that this oil pressure safety switch was a candidate.

Great news!!!! A pressure gauge on the fuel line would have made short work of this issue.

 

[ckuhtz]

Yes, I agree. I am investigating how I can safely and permanently have one plumbed into the line.

 

[Scott215]

Glad you found it