Starting a long sitting, 2003 Mercruiser 3.0 alpha one, with a gen 2 sterndrive.

jmav970

Cadet
Joined
May 10, 2021
Messages
9
Just looking for advice here. My boat has been sitting 6-7 years. Pumped out all the old fuel and put seafoam treatment and 10 gallons of fresh gas, took out the plugs (dry and relatively clean), filled cylinders with MMO, and let it sit 48 hours just to be safe. Turned the engine over by hand, turned smooth, no grinding, no noise, all the MMO that came out was perfectly clean, maybe just a touch darker. Dropped the lower unit, changed the impeller snd gaskets and the carrier seal, changed the starter (it was bad) changed the starter relay/slave solenoid, new trim fluid, drained and refilled gear lube, and greased all zerks while turning the engine by hand, changed the fuel filter (have extras) and
So here’s my plan, please tell me if I’m missing something.... hook up muffs, try to start the engine, if it starts run it for 10-15 minutes, drain the oil, refill with straight 40, run again for 10-15 minutes. Then drain the oil again, change the oil filter, fill with 25w40, change the fuel filter, put in new plugs, wires and distributor cap. Does that sound like a reasonable process? Am I doing too much? Something else I should do? Any hints/tips would be great! Thanks all!
 

Alumarine

Captain
Joined
Feb 22, 2005
Messages
3,745
The only other thing I might do is ground the coil, pull the plugs and engage the starter until the oil pressure built up.

I'd pull the plugs to make it easier on the starter.
 

ronaldreagan

Seaman
Joined
Sep 8, 2014
Messages
68
Don't be too surprised if you need to disassemble and clean the carb.... Very diligent description but multiple oil changes may not be necessary. I recently ran an engine that was not run for three years and had to clean out the carb and later replace the riser since it had rusted shut. (also replaced manifold and other cooling system parts for good measure)
 
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jmav970

Cadet
Joined
May 10, 2021
Messages
9
Thanks for the reply! I dumped some fuel in the carb last night and it ran like a champ, but as soon as that gas ran out, it died and wouldn’t restart. I discovered that my fuel pump wasn’t sending anything so that’s my project today, pulling it off and seeing if it needs replaced or is just gummed up.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
Messages
50,597
could be stuck anti-siphon valve, could be a variety of things. run the motor from a small gas can to rule out the boat side of things
 

jmav970

Cadet
Joined
May 10, 2021
Messages
9
could be stuck anti-siphon valve, could be a variety of things. run the motor from a small gas can to rule out the boat side of things
Never thought of that! If the pump works and the siphon is stuck, what would be the fix for that?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
Messages
50,597
Never thought of that! If the pump works and the siphon is stuck, what would be the fix for that?
pull the anti-siphon valve and shoot some carb cleaner in it.
 

ronaldreagan

Seaman
Joined
Sep 8, 2014
Messages
68
Same thing happened to me, no fuel to the carb. Turned out to be the screen was clogged at the carb end of the fuel line.
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,920
Initial change is enough. Start and run it like you stole it.
Agreed just change it and go. I've had engines sit for that long and run just fine. I usually take the plugs out and run it on the started until I see oil on the rocker arms
 
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