boat stalled out today

[boatman37]

hey guys. i know this will be difficult to diagnose over a forum but put the boat in today and was heading to my slip at about 1000 RPM and about 2 minutes in it shut off on me. no indication of anything wrong. just like it ran out of fuel or somebody shut the key off. its a 1986 merc 260. after a few minutes ii got it fired back up and made it to the slip. after getting everything settled in i started it back up (after visually checking the engine compartment) and it was idling at about 800 RPM then a little sputter but it kept running.

back story: the boat ran perfect last year. stored indoors under ground all winter with about 30 gallons of valvetech in it with no stabilizers. i changed the fuel separator last week and fired it up on the muffs and let it run for about 10 minutes and all was fine. today i filled the tank (added about 40 more gallons) at the gas station with 87 octane and added a fuel additive to offset the ethanol.

any ideas? i didn't leave the marina so couldn't open it up to see how it was at speed. i thought maybe an air gap from the separator but i would have thought that would have cleared itself in the driveway the other day. maybe the 30 gallons that was left in it all winter? any other additive i should add?

 

[Bt Doctur]

remove the fuel sep and dump into a clear container ,let sit a few minutes. see if there is a seperation line, Sounds like water in the fuel

 

[boatman37]

will do BT Doc. Thanks. i am thinking it is fuel related. would dry gas help? i think it contains ethanol though doesn't it?

 

[boatman37]

pulled the separator and poured it into a glass jar. no separation at all and no indication of water in it. i fired it back up. seems fine at idle now. could it have been an air lock?

 

[Rick Stephens]

Could have been. Could also be a cruded up anti siphon valve, a plugged vent, and how about the in port screen on the carb?

At least in a slip you can fire it up and stick in gear for a test.

 

[boatman37]

well went down to the boat today. took it out for a cruise and it ran fine. i did notice when i first pulled away from the dock it felt like it was sputtering a little like it was loaded up. i went about a couple hundred feet and it started clearing up and the RPM's started climbing (i was in a no wake zone so only running about 1000 RPM but it jumped up after it started clearing up).

this is a 1986 carb'd motor. last year i only gave it about 1/2 throttle then back it down prior to starting the engine. this year i started putting it to full throttle then back it down and starting it. my reasoning was to set the choke. would this be flooding up and loading it up?

 

[boatman37]

another update, yesterday i went back to only giving it a little throttle at startup and not setting the choke. seemed much better. i am going to assume that was my problem?