No Top End

[JTupper]

Hello, I am new to this site. I purchased a 2005 Mobius XLV with the 325 Indmar about 3 years ago. When I first ran the boat I could get 44mph out of it. Now i can only get about 32 and it wont hold it very well. Also doesn't seem to pull as hard out of the hole. besides that it starts and idles great if you didn't know any better you wouldn't think anything wrong. From reading other posts I would believe that I am carrying extra water in the drop keel section of the hull under the ski locker. I am new to inboards and only had experience with out board powered boats before. Is it fuel related, tune up, a sensor? any help would be appreciated. Thank you.

[z28ke]

I would try a replacing the fuel filter first. I had to replace on my 08 Outback V a couple years ago with similar symptoms. Easiest and least expensive place to start and fixed it right up.

[JTupper]

Thank you z28ke I will try that. As soon as all the ice melts, 20+ inches out there right now.

[boardman74]

It could be one of a 100 things, but the filter is a good place to start. What are the RPM's when your WOT? Is it smooth? Does it surge, or sputter? If you have enough water trapped under the floor to lose over 25% of your top speed your going to have a split hull come spring(from it freezing and expanding) so I really doubt that.

[mmandley]

I would go Fuel Filter,
Spark Plugs
Spark Plug Wires
Cap, Rotor

Once she is in the water you will know if you are caring a lot of nose weight because it will sit nose down in the water. Your swim deck will be higher then normal in the water.

If you do all those simple repairs, I would next be looking at the Carb.

[JTupper]

WOT RPM is about 4400. It pulls smooth, doesn't cough, sputter or anything like that. It just doesn't have the power it did before. also doesn't seem to be any less fuel efficient .It has never sat funny in the water or handled odd like a lot of water was sloshing around. Should I be treating the motor the same as an old school V8 in a muscle car? I guess a basic tune up won't hurt as suggested. Thanks for all the tips everyone.

[brain_rinse]

I would go Fuel Filter,
Spark Plugs
Spark Plug Wires
Cap, Rotor
...
If you do all those simple repairs, I would next be looking at the Carb.

Agree with Mike.


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[parrothd]

Do you have perfect pass installed?

[bergermaister]

Should I be treating the motor the same as an old school V8 in a muscle car?

Pretty much. Before you go swapping parts in the distributor have a look for corrosion on the existing stuff. I'd bet it's fuel or fire that's limiting you or a combination of the two.

Curious if you are noticing anything at the very top end of 4400rpm. A slight miss, surge, etc.

Unless you changed to a gnarly power prop and forgot to mention that... :confused:

[kaneboats]

Good question. Make sure cruise or PP is off. Also, you may want to check your throttle linkage. It's possible you are not putting the hammer down all the way or that when you do it is not opening the throttle all the way.

[zabooda]

Electronic ignition did that with mine. The second one I've replaced. It could have saved a carb rebuild had I caught that first.

[JTupper]

Perfect pass is off,running stock prop. I did check the linkage in the fall it it seems fine. at the dock I can get past 4400 more like 4600 -4700. Probably more but I didn't want to push it long with no load. I have had a situation where I hammer down to pull someone up and I over loaded the perfect pass servo and had to rewind the string. When it comes undone it will only go like 5 -10 mph. Does anyone now how to bypass that to eliminate that as a variable.

[parrothd]

That's why I was asking about the prefect pass. The servo motor is probably on its way out if it happens a lot.

How are you getting the speed? Via perfect pass/speedo or via a GPS.

My PP and speedo are way off sometimes, like + or - 15 mph. There's a small 4 wire connector by the paddle wheel in the bilge, if it gets wet you get incorrect speeds. Try using your smart phones and GPS app to verify what your speed is.


What's the max rpm under load? Is the prop messed up?