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Old 02-05-2017, 09:31 PM   #1
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I owned a pontoon with an outboard for many years, but now I have my first
I/O engine - so different! I bought a pristine '97 SR2000 with a carburated
5.7L Alpha One that was installed in '14 and has had minimal use since.

1. Took it out for first time and at NO WAKE speed it did not want to go in a straight line - left, oversteer, right oversteer, etc. I'm hoping that it was mainly due to the Quiksilver 48 A521P prop. 2 other props also came with the boat -
Mercury A45P21 (3 fins) and a Mercury A4518P (4 fins). Help

2. This baby goes great at speed, but idles like a Harley, even quit twice at idle, then easily starts right back up. I called a local marine dealer and he said it sounds like he should rebuild the carburater for $450-500. I put a can of Seafoam in the gas tank to see if that would help, but I haven't put her back in the water yet. Thanks in advance for your Help

I am a new member on the Central Coast of CA
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Old 02-05-2017, 10:08 PM   #2
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i would try quicksilver prop calculator to see what it recommends. The Alpha has a trim anode that is set to compensate for slow speed steering torque.

What carb do you have 2-4 bbl? At idle is the fuel a steady spray?
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Old 02-06-2017, 04:07 AM   #3
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So my trim anode is faulty?
I have a 4 barrel carb. I have not run the engine with the air filter cover off to watch the fuel spray - is it OK to do that, or is there a possibility of backfires?
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Old 02-06-2017, 01:11 PM   #4
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My last boat had the same motor and outdrive on it with the anode like that. I can say that the reason your boat steers like that is due to you hull design in the water. Anode doesn't help. After 6 years I even replaced it with a flat one and no change. Take any boat with that design of hull which is a large percentage of them. They all do it. Just takes getting used to it.

As for low speed idle, Seafoam will help it, but nothing beats a carb rebuild. Even something most do it yourselfers can do with a little help online.
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Old 02-06-2017, 03:11 PM   #5
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The prop would not impact bow wander. Bow wander is a result of over-steering. I find the detent for 'headway speed' is really a bit below 'no wake'. You can typically kick it 100 - 200 rpm and still be running at no wake. I can usually run up to 1,000 rpm and no be making a wake. The little extra speed reduces bow wander. The restis simply oversteering.

Prop size and pitch are dictated by RPM's at Wide Open Throttle. Most Mercruiser's max rpm range is between 4400 -4800 rpms.
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Old 02-06-2017, 05:32 PM   #6
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Thanks Richard. My boat has the exhaust pipes coming thru the transom above water level - very loud. Any suggestions on an affordable way to quiet lthem down?
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Old 02-06-2017, 05:34 PM   #7
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Thanks shrew. My boat has the exhaust pipes coming thru the transom above water level - very loud. Any suggestions on an affordable way to quiet lthem down?
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Old 02-06-2017, 11:03 PM   #8
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Quote:
Originally Posted by Tom D View Post
So my trim anode is faulty?
I have a 4 barrel carb. I have not run the engine with the air filter cover off to watch the fuel spray - is it OK to do that, or is there a possibility of backfires?
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Not faulty but not adjusted, you can set the leading edge to counter steering torque.

Always a possibility of backfire but if not doing so you can remove it for a short test anyway since you said it's an idle issue you only need to check it at idle.
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Old 02-06-2017, 11:05 PM   #9
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Tom regarding the exhaust can you post some pictures of the exhaust from the inside. A aftermarket kit was installed some bypass the factory exhaust others are set up to go either way by a switch. Can you tell is the factory y-pipe is still there?
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Old 02-07-2017, 02:15 PM   #10
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Quote:
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Thanks shrew. My boat has the exhaust pipes coming thru the transom above water level - very loud. Any suggestions on an affordable way to quiet lthem down?
That is not stock. It would have required that someone modified the Y valve that would divert exhaust and cooling water back through the transom assembly.

IIRC "Corsa" made a conversion kit. I think they might have even made a 'switchable' option to go between above water and outdrive exhaust systems.

The only real way to quiet that down would be to revert back to the stock exhaust configuration. Not knowing what has been done and how, I would have no idea what the cost involved would be.
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