97 Merc 200 carb, slow to plane out and no top end

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Blake_F

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I have a 1997 mercury 2 stroke V6 200 carbureted on my 18ft fisher bass boat. It’s ran great over the last couple years I’ve owned it. Put lots of miles and hours with not many issues. Recently I had a carburetor blowing out air and fuel so I inspected the reed valves and a few of them were chipped or broken. I’m sure they have never been replaced. I replaced the broken ones and put back together and she idled and started like a dream. Once I came out of the no wake zone and opened her up, it was very slow to get on plane, and would only top out at 40-45, I’m usually running 60-70. Brought it back and went back to the diagnostics. Checked throttle thinking maybe something got accidentally adjusted in the reed process, all carbs looks to be sinked and opening all the way. Checked compression and all turned out ok. Went to spark, all plugs firing. But when I did a drop test, top 2 cylinders have spark but no change in idle. This confused the hell out of me. I’ve heard of those bigger outboards with carbs idle on 4 cylinders then the other 2 kick in on high output, not sure if this is true or not?? Fuel seems to have no restrictions and is very fresh/clean. Took a flashlight to the reeds to check if something went wrong and those were all good as well. And ideas? I’ve missed most of the spawn and it’s really pissing me off lmao before the reed indecent, she ran fast, loud, and smooth like an old 2 stroke should
 
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Chris1956

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V6 Mercs do not have the 2+2 feature. Every cylinder on your motor runs continuously.

Reed valves almost never wear out. I doubt yours's needed to be replaced.

You might check timing at idle pickup and max spark advance. Maybe you messed something up when changing the reed valves.

Do all carbs get fuel? What do the spark plugs look like?
 
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Blake_F

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Chris1956 said:
V6 Mercs do not have the 2+2 feature. Every cylinder on your motor runs continuously.

Reed valves almost never wear out. I doubt yours's needed to be replaced.

You might check timing at idle pickup and max spark advance. Maybe you messed something up when changing the reed valves.

Do all carbs get fuel? What do the spark plugs look like?
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The reeds definitely needed to be replaced, about 5 were chipped or broken. Carbs are all getting fuel. Spark plugs are new, took it out again today and it doesn’t sound like it’s either not running on all cylinders or flooding. Really struggling when getting on plan that starts a heavy shake when I come off the throttle. But it won’t die
 
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Blake_F

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When I
Blake_F said:
The reeds definitely needed to be replaced, about 5 were chipped or broken. Carbs are all getting fuel. Spark plugs are new, took it out again today and it doesn’t sound like it’s either not running on all cylinders or flooding. Really struggling when getting on plan that starts a heavy shake when I come off the throttle. But it won’t die
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did the reeds I put all new gaskets on made sure everything was put back the way it was. Not saying I did everything perfect but followed pictures accordingly that I took before hand
 
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Chris1956

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Reeds were stainless steel?

If timing is good, and spark on all cylinders, carbs are next possibility.
 
jimmbo

jimmbo

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What were the Compression Numbers?
By Good Spark, can it jump a 3/8" Gap on all Cylinders?
 
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Blake_F

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I thought so too. So I examined the carbs. All were getting fuel and would quickly react when I choked air out. Tried squirting fuel/ oil mix in the carbs, it either flooded or no reaction. I’m not sure that the reeds were made out of that I got, but they are the OEM part# for that motor
Chris1956 said:
Reeds were stainless steel?

If timing is good, and spark on all cylinders, carbs are next possibility
Click to expand...
 
jimmbo

jimmbo

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Blake_F said:
The plugs on those don’t have a gap, they are open faced. Compression numbers are all between 108-110.
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I am not referring to Spark Plug Gap. However, to verify the Ignition System as Functional, it needs to produce a Spark strong enough to jump a gap, of 3/8". Saying the Spark is fine because you see it jumping the tiny Gap on the Plug means Nothing, because as Air Pressure rises, during the Compression Stroke, the Voltage required to jump that tiny Gap increases rapidly. Hence the need for it to jump a large Gap at Atmospheric Pressure
 
Dukedog

Dukedog

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Blake_F said:
Electrical is a little above my pay grade hahah. Not sure how to diagnose a bad stator or anything electrical. far from my strong suit
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send me an email address and i'll send ya an oem manual in pdf.. will tell how ta do 'bout anything with your motor....
 
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Blake_F

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Oh I see, how would I go about testing that?
jimmbo said:
I am not referring to Spark Plug Gap. However, to verify the Ignition System as Functional, it needs to produce a Spark strong enough to jump a gap, of 3/8". Saying the Spark is fine because you see it jumping the tiny Gap on the Plug means Nothing, because as Air Pressure rises, during the Compression Stroke, the Voltage required to jump that tiny Gap increases rapidly. Hence the need for it to jump a large Gap at Atmospheric Pressure
Click to expand...
 
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