Any ideas of engine loss of power

[YellowWakesetter]

Ok, so we go out to the lake and we are boarding for about 2 hours. I started out using the perfect pass, I have the perfect pass set up to run around 2800 RPM, which is anywhere between 19-21 mph. The boat was doing good then it seem like it wouldnt hold at 19-21 mph, it was dropping to about 13-19, then when I was towing a friend the boat did something funky, the best way I can describe it is that it "surged". It felt like the tranny was messing up the rpm was the same but for a split second there was no power almost like the clutch slipped. I had the wedge down and the ballast full, so I shut it down and checked all of the fluid they looked good, I added a little bit of tranny fluid. After we rested and had lunch we headed home with no problems. So when I got home I started researching and found this webpage and here I am, I spent the last couple day just searching this webpage to see if I could find an answer and I havent. What do you guys think it could be?????? (I want to run the boat again to check it out this weekend but I will be out of town, Puerto Vallarta Vacation )

My ideas

1) clogged injector

2) Clutch

I read something about the knock sensor, what is that???

One more question, what is the throttle protector?? I was looking around my engine and seen that.

[UWSkier]

I'd check all throttle linkages and cables first. When they get loose, PP can do some funny things.

[D-GOOSE]

If it only happened when PP was on, then I would have to say its with in that area. Some time's the control cable will come loose and lower your speeds. If your RPM's stayed the same but you slowed down then it would be in the trans. There are no clutchs just hydraulic psi.

A few things off the top of my head that it could be is a clogged strainer, pinched line or the pump going bad.

If the eng changed RPM's then you would have a fuel problem. That most likely would be a fuel filter.

[YellowWakesetter]

Throttle linkage, sounds good, I never looked into that. ............ Thank you guys!!!!!!!!!!!!!!

[notoutenough]

I had similar problems recently that were fixed by replacing the fuel filters. My boat would run fine for some time, then would suddenly have a loss of power. I would only be able to go about 28-30 MPH even at WOT. The engine did seem to bog down at WOT though.

--Robert

[Sunsetter95]

I had similar problems recently that were fixed by replacing the fuel filters. My boat would run fine for some time, then would suddenly have a loss of power. I would only be able to go about 28-30 MPH even at WOT. The engine did seem to bog down at WOT though.

--Robert

I agree, first thing, fuel filters. Unless you just had them changed this season.

[YellowWakesetter]

how hard is it to replace the fuel filter?? I know where mine is located, but do I need a special tool?? On my truck i needed a special tool.

I had similar problems recently that were fixed by replacing the fuel filters. My boat would run fine for some time, then would suddenly have a loss of power. I would only be able to go about 28-30 MPH even at WOT. The engine did seem to bog down at WOT though.

--Robert

Yeah mine seems to do the same thing, lets hope that is it.

[D-GOOSE]

If yours is an inline filter it should just have 2 hose clamps that you unscrew. If its a spin on then its just like a oil filter.

Your truck takes a speical tool because your fuel tank has the fuel pump in it and puts PSI in the fuel line. On your boat the fuel pump is most of the times after the filter.

[aneal000]

This is odd one huh?

In RPM mode pp tries to hold rpms and doesn't care about boat speed so as long as PP is getting the right signal then anything goes. It would seem that a tranny problem would be logical, as if a load was released from the motor it would try and rev higher - or in your case pp was holding that parameter so the other option is the boat slows down. My first guess, but I don't know much about the insides of these trannys. My second guess would be something physically was slowing down the boat. Since you say the motor was still maintaining 2800RPM (did you notice any difference in sound? sound like the motor was speeding up, slowing down, or surging?) you could conceive that if a big piece of debris (flotsam or jetsam - I just like using those words any chance I get) was to get caught in the tracking fins or wrapped around the propshaft you would slow the boat speed down while not changing the RPM. You stopped and sat for a while giving the debris a chance to "move on" and everything worked fine.

No telling really with this one. I doubt it is fuel related if the RPM's truly didn't change. If the motor is spinning x rpm then the boat should be going x speed unless something is limiting it physically. You say the boat held 2800rpm then something was limiting it's speed - can't be a fuel problem or you would of lost RPM which would of equated to a loss in speed.

edit, the knock sensor is located on the lower side of the engine block, it screws into the side of the block and has one wire attached. It is used to detect engine knock and I believe the computer uses this signal to adjust fuel/air ratios.

Edited June 28, 2006 by aneal000

[YellowWakesetter]

Ok, so now I am back from the Mexican Vacation so I pull the boat out to start checking thing over, I hook up the fake lake plunger and turn the water on then I start the boat ......................... it is running now problem except that I do not see water coimg out of the exhaust like usual so I shut the engine down and double checked the fake lake then I proceed to work my way back to the impeller, I just got the impeller changed in April so I should be working fine .......... after pulling the plate off I stuck my head down there and was checking out the impeller. Well I am not an expert but it looks like the impeller is not put on right the fins in top of are sticking straight out and the fins on the bottom at smooshed against the bottom. I have never change an impeller and had a hard time even finding the thing, so I mad and appointment to have the shop look at it.

Needless to say I am thinking that the reason why my boat seemed to be running bad was that it was overheating! I hope and pray I didnt do any major damamge. It does make sense to me why the boat cut out. As soon as it cut out I shut it down and let it cool then I drove it back to the dock.

[YellowWakesetter]

I had the impeller replacd and there was sand in there, the shop thinks that is what may have happened. Moral of the story dont beach your boat!!!

[UWSkier]

I had the impeller replacd and there was sand in there, the shop thinks that is what may have happened. Moral of the story dont beach your boat!!!

Shouldn't ever do that anyways.

[RoverOn]

I had the impeller replacd and there was sand in there, the shop thinks that is what may have happened. Moral of the story dont beach your boat!!!

Or if you do...don't do it under power and don't fire the motor up until you are well away from the shore...

[aneal000]

Well I am not an expert but it looks like the impeller is not put on right the fins in top of are sticking straight out and the fins on the bottom at smooshed against the bottom.

Nope, this is normal. Quit worrying about overheating problems.

Bad picture but it kinda gives you the idea of normal...

[MoonDawg]

There is a filter beyond the Raw Water Pump that may be clogged up with lake weeds, sand and chunks of old impeller. If that filter is clogged then your motor could get hot and your MEFI controller will limit your boat RPM to around 2200 RPM (Limp Mode).

It is easy to clean...just follow your water line from the pump to find it. The filter is a round canister with a wire mesh inside. Just clean it out and go.

[UWSkier]

There is a filter beyond the Raw Water Pump that may be clogged up with lake weeds, sand and chunks of old impeller. If that filter is clogged then your motor could get hot and your MEFI controller will limit your boat RPM to around 2200 RPM (Limp Mode).

It is easy to clean...just follow your water line from the pump to find it. The filter is a round canister with a wire mesh inside. Just clean it out and go.

Malibus don't have filters. At least not the ones I've worked on ('01 and later).

[mlange]

I think MoonDawg was referring to the trans cooler.

Mike

[hotrodbowtie]

I think I would look at the shift linkage. If the rpm's are staying where they belong then your motor is running fine. If it were overheating and slowing down, rpm's would be following it down. Rpm's and speed are connected with the drive train. If the engine is running fine the it has to be something in the drive train.

JMHO. Good luck

[gooddog]

the best way I can describe it is that it "surged". It felt like the tranny was messing up the rpm was the same but for a split second there was no power almost like the clutch slipped. I had the wedge down and the ballast full,

If there was any chop on the water it is possible that what seemed like a clutch slipping could have been cavitation on the prop, especially with a lot of rear ballast.

[YellowWakesetter]

took the boat out yesterday it ran perfect!!!! Now onto the next problem. We were boartding yesterday and I filled the ballast and when it was time to drain the ballast it wouldnt drain.

What is the best way to drain the ballast? Where would the drain pump be? I hope the pump didnt go out