Rinker '95 Bravo 5.7L carbed, mechanical fuel pump . Starts, quits immediately

[rocklydockly]

ENG: 0F287508 457B110HS
1995 MERCRUISER 5.7L BRAVO

Boat starts well and immediately dies. Ran well 1 week ago, no issues. 3 day trip coming and I'm hoping for reliability.

carb rebuilt 1.5 years ago
gas in the float bowl
accelerator pump working

I'm thinking fuel delivery, not electrical or else it wouldn't start at all. New Fuel water separator last week.

Any suggestions?

 

[alldodge]

immediately dies

If its dying like the key was turned OFF, then its electrical. With gas in the carb and the fuel pump stops it would take a little bit before it dies.

My first thought would be the key switch. Measure the voltage on the + side of the coil and see if it remains when motor dies

 

[Mad Props]

Maybe clogged idle circuit in the carb? Accelerator pump could be shooting fuel into the throat to get it started but then not getting fuel to idle??

I agree with Alldodge tho, if its immediately dying, its probably not fuel, but if it kinda stumbles for a second and dies out, it could be fuel.

 

[Scott Danforth]

As AllDodge pointed out, its electrical since a carbed motor would run on the fuel in the bowl for 30 seconds or more under load and up to 4 minutes at an idle

most likely either of the following

the crank feed to the coil works and the run feed from the ignition switch doesn
the ignition switch is bad and only powers the I terminal (purple wire) from the start position