2007 Moomba Outback Indmar 325 bogging down / misfire, rough idle especially when hot

My 2007 Outback with Indmar 325hp is bogging down especially when loaded down and hot. 225 hours - excellent shape and well maintained.

This is a new issue which started this summer when wake surfing. Happened when loaded down with 1000 lbs of ballast and people on the boat. Ran fine for a while but when heated up - after an hour or so - would bog down bad and idle rough. When the engine cooled off would run much better - but still bog down in odd ways - for instance at 3000 rpms the engine would just start to bog down by itself to 2000 rpms or so and then run back to 3000

I changed the plugs, fuel filter and Distributor. Everything worked great for about 20 hours. Now doing the same thing again. Something is wrong - not sure where to start?

Worried we are pushing this boat to do more then it can? Appreciate any advise.

It's propped wrong for surfing. You probably need a lower pitched prop. What's on there right now?


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Thank's of your input.

It has the original factory prop? It seems odd that we have surfed for the past 4 summers owning this boat - and now issues?
what do you mean lower pitched prop? You think that alone will fix this issues? open to any suggestions.

Thanks

Doesn't sound like you're loaded with 1000lbs of ballast. I put about 2800lbs in my 06 LSV to surf and have (I assume) the stock prop. Sounds more like a mechanical issue to me if htengine RMPs drop. Mine struggles at times to get to the speed on the perfect pass but my RPMs remain steady.

Have you changed the impeller recently?


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2nd Impeller check!
Also do you have a sea strainer on intake and/or run in water that may have debris?

If that all checks out, you could have either a bad thermostat or a bad circulation pump.


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Originally Posted by viking

2nd Impeller check!
Also do you have a sea strainer on intake and/or run in water that may have debris?

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Come to think of it mine did the same briefly after we had a wicked storm and the lake was full of debris. Where do you check the impeller and where could there be a screen if you don't have the strainer? I just took the hoses off the water pump and ran my fingers inside the pump. I also took the hose that comes from the floor to the V-drive and looked in there. I had no debris in the lines or pump and impeller felt like it was intact.

Sorry to highjack your thread.

To check the impeller remove the plate of the front of the raw water pump that is attached to the crank pulley. Be careful when you remove the plate as there is a very thin almost foam like gasket that seals the plate to the pump housing. If you tear it or damage it then it needs to be replaced with another one or it will leak like a sieve. Look for missing blades on the impeller pump. If they are gone then track the outlet side of the pump up into the thermostat housing and remove that hose and look inside it and around the thermostat housing for the missing pieces of rubber. Those need to be removed so that they don't clog up water passages in the engine and cause hotspots that could lead to serious problems.


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Quote:

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Originally Posted by Stazi

To check the impeller remove the plate of the front of the raw water pump that is attached to the crank pulley. Be careful when you remove the plate as there is a very thin almost foam like gasket that seals the plate to the pump housing. If you tear it or damage it then it needs to be replaced with another one or it will leak like a sieve. Look for missing blades on the impeller pump. If they are gone then track the outlet side of the pump up into the thermostat housing and remove that hose and look inside it and around the thermostat housing for the missing pieces of rubber. Those need to be removed so that they don't clog up water passages in the engine and cause hotspots that could lead to serious problems.


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Thanks!


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