Boat starts and dies

Does it rev up if you apply throttle?
If yes, it may be the Idle Air Control (IAC).

Some reading for you:
http://www.clubsearay.com/index.php?threads/official-240-sundancer-thread.436/

Best of luck and welcome to CSR!

 

Possibly bad battery then... computer shuting down at low voltage.
Load test the battery.

 

Your voltage drop is excessive and won't let the ecm fire the plugs. Most likely corrosion on 90 amp fuse at the starter or the ground cables attached at the rear of the block.

 

How about a heavy gauge jumper wire from battery (+) to the orange wire at the back of the alternator, for testing purposes. If that rectifies your voltage issue, that would also point to the 90 amp fuse being an issue.

 

You can do your voltage drop anywhere along the way. I usually start at the 50 amp breaker cause it's easy to get to. I'll do the negative drop from the battery to the ground stud on the block.

 

All good advice, above. Need some clarification.

What do you mean by "doesn't start"? To most of us, that would mean it turns over but it doesn't actually fire/start. Or, do you mean it doesn't even turn over? We're getting bits and pieces of info so it's kinda hard to give some accurate advice. Post as much info (detailed) as you can.

You could have multiple things going on - history of how the engine has been running/sitting unused/etc would be good to know and whether there's been recent service.

Remove your battery connections, clean, inspect, reinstall TIGHT. If you still have issues, then start with the other ideas.

Check your breaker - I believe you have one near the battery (black, square).

 

Years ago, I had a jetboat with a 5.7L GM V8. One day we splashed it and I started it right up. As soon as I let go of the key and it dropped back to "RUN" position, the engine immediately died. I did that a couple of times and then started checking things. Turned out to be the wire to the distributor had came off of the back of the switch. Somehow the distributor would get power while the key was in start but as soon as the key went back to run, no spark.

That was when I fell out of love with those wire end terminals with the fork looking end. It's nice to not have to remove the screw to remove or install but there can be a price. I was glad that wire didn't jump off in the middle of the "Snow Hole" on the Salmon River.