Evinrude 33HP throttle problems

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charles dennis

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Sep 4, 2005
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I have a 14'Sportscraft and the top end speed was only 4.5 mph with my 33HP Evinrude. I had the motor checked before I put in the water and was told it ran fine. What could possibly be the problem?
 
Joe Reeves

Joe Reeves

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Feb 24, 2002
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Re: Evinrude 33HP throttle problems

The cavitation plate just above the propeller should be approximately 3/4" below the keel (bottom of the boat at the transom). Is it?<br /><br />Does the engine race up to full throttle and the boat goes nowhere (assuming the cavitation plate is where it belongs). If so, the usual cause is a faulty propeller hub (slipping).<br /><br />We need a little more detail explaining exactly what the engine is doing or not doing.
 
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charles dennis

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Re: Evinrude 33HP throttle problems

The cavitation plate is approximately 1.5" below the keel. The engine did not race to full throttle. It never opened up at all, just seemed to be at idle speed. The only time it did open was when my father in law reached inside below the flywheel and manually adjusted the throttle. The motor seemed to go faster in reverse than in forward gear.
 
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Paul Moir

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Nov 5, 2002
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Re: Evinrude 33HP throttle problems

When you advance the throttle (engine off and set in forward - you may have to rotate the flywheel a bit for it to engage) you should see the plate up underneath the flywheel turn, and simultaneously see the throttle valve on the carb open (as actuated by a roller that follows a cam on the plate beneath the flywheel. Eventually the plate should stop turning, caused by a stop near where the spark plug wires come out of that. After that, a linkage on the throttle arm should take over and open the carb's throttle valve the rest of the way.<br /><br />So, what part of that picture isn't happening here?
 
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charles dennis

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Sep 4, 2005
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Re: Evinrude 33HP throttle problems

The linkage on the throttle arm did not take over. I think I got that adjusted last night. Thanks for the help. The cavitation plate is lower than the 3/4" that Joe Reeves said it should be. Should I raise the motor? Being lower than where he said it should be what effect does that have on the motors performance?
 
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Paul Moir

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Re: Evinrude 33HP throttle problems

You can try it out. It'll make the boat go faster (by reducing drag from the gearcase), but just make sure you're still pumping cooling water well at idle and WOT.<br />But there's no point in fooling with that until you've got the engine running properly.
 
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