Starting 2 Stroke 150 hp Outboard

Chip S

Chip S

Active Member
Jun 17, 2019
432
Bordentown, NJ
Boat Info
1993 Sea Ray 200 Overnighter
Engines
2023 Mercury 150 hp Four Stroke Outboard
Once I get my 150 hp 2 stroke outboard started it runs great. It's taking me a lot of trial and error though to initially get it started. Here's the list of parameters I'm working with:

Fuel bulb: squeeze or not squeeze, if squeeze, how many times
Push in choke (at key): use or not use
Throttle: leave in idle neutral (straight up) or push forward in neutral

Thanks for any suggestions.
 
Squeeze the fuel bulb until you feel resistance. The bulb should be hard, indicating that you have filled the carb.

On a cold engine, push in the choke while engaging the starter. Once it fires release the choke. When the engine is warm, no need for choke when you re-start.

Before starting, disengage the gearshift by pressing the "throttle only" button and advance the throttle lever "slightly". When the motor starts, retard the throttle until the engine is running at about 1000 rpm and let it warm up. When you are able to retard the throttle all the way back without the engine stalling, then you're ready to go.

If the above procedure doesn't work, you need a carb rebuild, new spark plugs, and / or fresher gas, etc, etc. I have motors older than yours, but they all have been thru the shop a few times.
 
Had a neighbour that always had a terrible time trying to start his merc outboard.....he always left the engine tilted up out of the water when not in use...could the carbs have drained while inclined ?? He would just lower the motor and crank, crank crank...not give the time for fuel system to pressurize.
 
Timeflys said:
Had a neighbour that always had a terrible time trying to start his merc outboard.....he always left the engine tilted up out of the water when not in use...could the carbs have drained while inclined ?? He would just lower the motor and crank, crank crank...not give the time for fuel system to pressurize.
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I also keep my engine up when not in use. If the carbs are draining that would explain why it takes a while to start it the first time of the day. I leave the engine down during the day and it starts up on the second turn of the key every time. At least I might have a reason now why it takes longer to start after I bring it down from the up position.
 
Chip S said:
I also keep my engine up when not in use. If the carbs are draining that would explain why it takes a while to start it the first time of the day. I leave the engine down during the day and it starts up on the second turn of the key every time. At least I might have a reason now why it takes longer to start after I bring it down from the up position.
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My '94 135 Blackmax drains when tilted all the way up for trailering, not sure at what point/angle they start to drain though. Before I head out to the ramps, I like to fire her up on the muffs in the drive to do a system check. When I get to the ramp, I always have to reprime quite a few pumps.
 
I learned from my 1970 Harley chopper. Kick start only. You learn how important priming the carb and clearing The cylinders are to starting the damn bitch.
But once it fires...I admit I get a stiffy. :rolleyes:
 
If you trailer a boat the ONLY time the engine should be up is on the highway. Even then, "up" means only high enough to clear the road.

Keeping the motor up out of the water while moored is a different story.

Regardless, if gas is draining, that's what the bulb is for. Personally, my gas is always drained. Just before shutting it off I pull the plug and run it till it stops. Keeps the carb much cleaner. Been doing that for 58 years now and all my motors start up second pull.
 
GypsmJim said:
If you trailer a boat the ONLY time the engine should be up is on the highway. Even then, "up" means only high enough to clear the road.

Keeping the motor up out of the water while moored is a different story.
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My boat is in the water tied to a dock during the season and I keep the outboard up out of the water to prevent growth. When I'm using the boat for the day I keep the outboard down in the water, even if I stop to get lunch somewhere. Gas draining from the carbs is consistent with what I'm seeing since it is only difficult to start when I first get to the boat. Now that I understand what's happening, I will definitely continue to keep the outboard down in the water while I'm eating lunch, refueling, etc. At the end of the day, though, I will continue to keep it up out of the water to prevent growth. The extra difficulty with the initial start is well worth not having to worry about the growth that would occur if I left it in the water.
 
Chip S said:
My boat is in the water tied to a dock during the season and I keep the outboard up out of the water to prevent growth. When I'm using the boat for the day I keep the outboard down in the water, even if I stop to get lunch somewhere. Gas draining from the carbs is consistent with what I'm seeing since it is only difficult to start when I first get to the boat. Now that I understand what's happening, I will definitely continue to keep the outboard down in the water while I'm eating lunch, refueling, etc. At the end of the day, though, I will continue to keep it up out of the water to prevent growth. The extra difficulty with the initial start is well worth not having to worry about the growth that would occur if I left it in the water.
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All makes sense. You are doing everything right.

If you still have problems after using the bulb to pump her back up, I might suggest simply replacing the bulb with a new one. Possibly your bulb has lost efficiency and you are not actually filling the carb back up.

In my experience, bulbs have a finite life span and once they get "hard" (not easy to squeeze) they are past their life span. Simple coupleabuck expense.
 
If you cant get the bulb to get firm after just a few pumps try replacing the bulb. If it still doesn't not get hard you probably need to think seriously about replacing your fuel lines, they don't last forever, I think its recommended they get replaced every ten years.

The reason you probably get fired up easily when warm is the fuel may be slowly draining back if there are tiny leaks letting air in but not enough to let fuel out.
 
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