boat wont move!

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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UPDATE- cant get it above 10 knots now. When I put the earmuffs on it, on land, I can get the RPM to 6,000 easily. Is it something else; I notice the boat does shake a bit, but the engine doesn't sputter and starts OK. Any ideas? Thanks...

stop reving the motor on the trailer.

the hose can only keep up to about 1500 RPM, and it proves absolutely nothing as the motor would spin there with only 2 cylinders firing, which is probably whats going on since it is shaking the boat.

you most likely toasted the impeller now.
 

massimofinance

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Oct 30, 2004
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497
Are my risers / manifold going bad?

1999 Sea Ray Sundeck 210. Mercruiser I/O 5.0 sterndrive, AlphaOne outdrive. I posted a few months ago an issue I had that I cant get it to get to plane over 11 knots and no one here knew why this was since I addressed all the usual suspects. Sorrt, couldn't find the post. When I had engine out service a few years ago, I remember the mechanic telling me the risers and manifolds weren't in the best shape, but should be fine to put back in, which he did. Now I am thinking that may be why I have no power- does that make sense? Is the engine toast now? worth fixing? What is symptoms of bad risers and manifolds? loss of power, louder than normal running? thanks.
 

GA_Boater

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Found the original thread and moved the above post for consistent advise.

You dropped the ball back in July. No update after changing some filters, so now you're chasing manifolds and risers.

Has the carb been rebuilt? Ever do the recommended compression test? Spark checked?

Advice is only good when it's followed.

Also the original thread was in the wrong section - Now fixed.
 

massimofinance

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Thanks for the assistance. I never rebuilt the carb, nor did I do the compression or spark test. That will be my next attempt. appreciate it.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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if the risers and manifolds needed replacing 6 months ago, then there was water leaking into the cylinders causing damage 6 months ago.

so now pull the manifolds and inspect. you may be pulling the motor and rebuilding/replacing.
 

Rick Stephens

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Devil is always in the details. Start from the beginning and plan your diagnosis. First is do not spend money on parts until you have checked things out and actually found faulty parts. Often see where someone posting about looking for a problem and their first post has a huge list of what they already replaced - without result. I applaud you for not doing that!

Start with a compression check. To do said compression check, warm the engine up on muffs first - make for sure and for certain that you are getting water flow out the bypass ports in the transom within a minute. No reason to ever rev a motor up over 1500 RPM under no load - meaning don't 'test' your motor's ability to do high RPMs without a load on it. That's doing nothing but possibly breaking something. With the engine warm, pull the plugs and inspect them carefully as they are each removed. Are any of them wet? Rusty? Properly tan colored? Then do your compression check on each cylinder while the motor is warm. Rotate the engine through 5 compression cycles to get a reading on each cylinder. You can leave all the plugs out while you do this and it will take less battery power. I like to label the plug wires as I pull them off, so maybe I have a chance of getting them back in place correctly without having to run the firing order from scratch. Then I double check that they really are right and the firing order is correct before starting the engine again. Way too easy to get them plugged in wrong.
 
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Scott06

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As mentioned start with a compression test as it is possible you had leaky manifolds and elbows.

if that is ok(135-155 psi) move on to checking ignition and carburetor. Check spark at the plug with a $10 spark gap tester, should be nice blue spark that jumps at least 3/8”. If not renew the cap rotor plugs and wires.

If spark tests ok check the timing with timing light including total advance. if that’s ok verify fuel pressure and then look at rebuilding the carb.

were assuming that the boat didn’t take on a bunch of water below the floor, have a dirty bottom (slip boat only) and youth have a reasonably correct prop pitch on there? Like a 19-21”
 
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massimofinance

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Oct 30, 2004
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all great advice and will follow it this time! thanks so much. and yes, the boat never took on a substantial amount of water, bottom is super clean (dry sail) and new prop with a 19 pitch.
 

tank1949

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Apr 4, 2013
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Swapped out the tiny carb fuel line filter. Old one looked fine. What would it look like if it were bad? The fuel line enters the fuel tank via an aluminum(?) fitting. Is there a filter there as well? Should I remove it and clean it as well I’ll see how it runs Saturday. I want to pull the carb and have it rebuilt but no one will do it locally- is there a mail-away service?

If you have small inline carb filter in hand, try blowing through. If you can, it should be ok, but they are cheap so I'd replace it!
 

tank1949

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all great advice and will follow it this time! thanks so much. and yes, the boat never took on a substantial amount of water, bottom is super clean (dry sail) and new prop with a 19 pitch.

If all the above suggestions checked out, and you are still having problems, you may have fuel line or air vent hose restrictions that prohibit fuel volume that is needed. Yoy may also have an anti-syphon valve that has become crudded up and too restrictive. )I had that too) . You can buy a cheap V8 automotive fuel pump (4-8# pressure) for < 50 bucks. Attach it to your external fuel filter and measure fuel flow. I had a mud dobber nest clog up my air vent line one time that nearly drove me nuts until by luck I saw the added mud. Normally, the lines have a screen. Mine had corroded. LOL
 
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massimofinance

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Oct 30, 2004
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Circling back with everyone. I took the advice here and I discovered my issue- it was the spark plugs. They hadn’t been changed in a long time and were pretty black. The boat is now running great again. Thanks again for all the advice- sometimes its the standard maintained things I guess...
 

Scott06

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Apr 20, 2014
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Circling back with everyone. I took the advice here and I discovered my issue- it was the spark plugs. They hadn’t been changed in a long time and were pretty black. The boat is now running great again. Thanks again for all the advice- sometimes its the standard maintained things I guess...

It’s always the simple sh$t...
 
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