Acceleration Bogging

[Rooster Tail]

Howdy all, I bought my first Malibu a couple of weeks ago, and have been following a couple of threads as I get to know the boat. I've been going through it doing most of the standard maintenance, since I can't be sure when the last time it was done; i.e. fuel filters, themostat, clean fuel, cap & rotor, and I've got a Grobe impeller on the way. The only thing that is keeping me from falling completely in love with the boat is an engine bog that I get when I go from in-gear-idle to WOT.

I don't notice anything significant if I ease into the throttle, but whenever I go completely wide open from idle, the engine sounds like it is flooding. This only lasts about a second, then it seems to recover and take off. The engine idles fine, and WOT is fine once I'm past the transition from idle, but that pause is irritating, not to mention I hate hesitations when I'm on the skiing end of the rope. I may be imagining things, but it seems more noticable after the boat has been idling for a few minutes, as I inevitably need to as I work with my kid.

I've searched on every related topic I can think of, but haven't found any identical issues. Does anyone have any suggestions? I'm thinking about looking into the IAC or MAP sensors next, but would appreciate advice from those of you who are already wise in the ways of Malibu. I've also heard that strange things happen as the coolant temp sensor goes bad, so I've got that on my list of options as well.

One last thing, I bought the boat in San Diego, and brought it back to Utah. I can't imagine why the elevation change would cause this issue in an EFI engine, but I'll just throw that out there.

Thanks in advance for any advice.

[Shine]

I cant say for engine issues, but maybe too much prop at altitude...

There are several prop experts around that may chime in. What prop is on it?

Edited August 25, 2009 by Shine

[chris.ault]

I had the same problems with my 99 Response LX. I changed both fuel filters and the throttle position sensor, and whammo! problem solved. I changed the TPS because the idle was hunting at times and presented this symptom after the bogged-down engine problem started.

How controlled is your idle speed? you may want to try the TPS, mine was only $80 or so. The Idle Air Control valve was about double that but I did not need to replace it - you might.

[Rooster Tail]

Nothing exotic for a prop, 3 blade 13 x 13 SS. Forgot to mention that I also put a new TPS on (in addition to changing both fuel filters). The old one didn't feel right once I took it off, so I went ahead and replaced it, but alas, the bog remains. Don't have any problems with idle speed/RPM.

[eyepeeler]

You may want to check the screen on the fuel pump.

[JBuck]

Maybe I missed it, but you may also need to check the plugs and wires.

[electricjohn]

Check for vacuum leaks

[Fsttyms1]

Check for vacuum leaks

Agree. I was having similar issues recently (was going on for about 6 weeks) and thought it was my carb. Well a few weeks later i noticed my oil was getting milky one day. Narrowed it down to the intake mani gaskets. The bolts were hand tight. Replaced the gaskets and retorqued the manifold and the issue went away. (i also while in there replaced the head gaskets and retorqued the head bolts and intake after a few hours of operation and they needed it).

[skier92]

Definitely go for the screen in the pump inlet. Most likely and easiest to do. Remove fuel hose, pull out screen (carefully) clean, re-assemble.

[Rooster Tail]

Confirmed that it is not a vacuum leak. Will check the pump screen before I take it out tomorrow. If I get time, I will probably replace plugs and wires, as that was already on my list of things to do.

[Baddog]

Too lazy to go back to OP, did you change the cap and rotor?

[mayfike]

I also have a 2000 Sunsetter LXI. Mine has about 750 hours on it.

My engine also momentarily lagged when under "load" (accelerating and/or higher end speds).

I'd changed all the plugs/wires/cap/rotor/fuel pump.

These engines (monsoon 325) have two fuel filters. One mounted on the back/passenger side of the engine and one mounted near the fuel tank. My fuel filter near the fuel tank was nearly completely blocked and could not keep enough gas flowing to the fuel pump.

Also--I think--that the lack of fuel getting from my first fuel filter to my fuel pump caused a high pitched whine from my fuel pump that normally should not be there (noticable about two seconds after I turn my key to the "on" position when the fuel pump primes, but before I actually start my boat. Also noticable when running the boat). Once I replaced the first of the two fuel filters, this whine went away.

Check out the posts on this website listing the engine parts numbers for Indmar for fuel filter and fuel pump numbers. The filters I removed were Napa Gold 3481 (mounted on engine) and Napa Gold 3033 (mounted near fuel tank).

Good luck to both of us!

Edited August 31, 2009 by mayfike

[InvisibleMask]

I had a similar problem on my brand new 23LSV, less than 10 hours. Ran fine at over 10mph but during take off it bogged. Sucks when you are trying to wakeboard and pull people out of the water!

Turns out a hole burnt through the big rubber exhaust tube. A piece was defective causing this. Exhaust fumes filled up my engine compartment (and water spraying everywhere in there) but I didn't notice it until I opened it up while it was running. Then instantly saw something was very wrong.

Had a local boat shop fix it, 10 hours later, same thing happened again.

Malibu replaced the defective peice and i hope all is good now.

By the way, how I knew it was probably exhaust related is the boat ran fine if I had the blower on all the time. As soon as I turned if off it started bogging again.

[Rooster Tail]

Thanks for all the help, here's a shotgun update:

Yes, I changed the cap & rotor, put brass on because it's worth the extra couple of bucks. Also changed both fuel filters, but with no performance change.

Will open the covers next time I am out on the water to look for exhaust leaks. Thanks.

Finally got a new MAP sensor installed before I took the boat out on Saturday. The first hour at the lake was awesome, finally got the boat I expected. But then, tragedy struck. Once we had worked our way through all the veteran skiers/boarders and started teaching the youngsters, the acceleration bog returned. After some experimenting, I've determined that it happens primarily when the motor gets hot. When idling around a learner, the boat heats up to 180-190 fairly quickly, and it bogs on takeoff. Doesn't seem to overheat at operating speeds.

New impeller should arrive this week, and I will check the tranny cooler and flush the hose as long as I have my tools out. That seems to be the most obvious solution. Will also clean the fuel pump screen when I get under there. Mallory wires and NGK plugs as soon as the wires arrive.

Will post any updates, but am still interested in anything I haven't considered to this point. Thanks again.

[Baddog]

Thanks for all the help, here's a shotgun update:

Yes, I changed the cap & rotor, put brass on because it's worth the extra couple of bucks. Also changed both fuel filters, but with no performance change.

Will open the covers next time I am out on the water to look for exhaust leaks. Thanks.

Finally got a new MAP sensor installed before I took the boat out on Saturday. The first hour at the lake was awesome, finally got the boat I expected. But then, tragedy struck. Once we had worked our way through all the veteran skiers/boarders and started teaching the youngsters, the acceleration bog returned. After some experimenting, I've determined that it happens primarily when the motor gets hot. When idling around a learner, the boat heats up to 180-190 fairly quickly, and it bogs on takeoff. Doesn't seem to overheat at operating speeds.

New impeller should arrive this week, and I will check the tranny cooler and flush the hose as long as I have my tools out. That seems to be the most obvious solution. Will also clean the fuel pump screen when I get under there. Mallory wires and NGK plugs as soon as the wires arrive.

Will post any updates, but am still interested in anything I haven't considered to this point. Thanks again.

Typical temp is 160F so I am guessing you will find a nasty impellor or crud built up on the tranny cooler. Good luck and let us know.

[mbaratelli]

Howdy all, I bought my first Malibu a couple of weeks ago, and have been following a couple of threads as I get to know the boat. I've been going through it doing most of the standard maintenance, since I can't be sure when the last time it was done; i.e. fuel filters, themostat, clean fuel, cap & rotor, and I've got a Grobe impeller on the way. The only thing that is keeping me from falling completely in love with the boat is an engine bog that I get when I go from in-gear-idle to WOT.

I don't notice anything significant if I ease into the throttle, but whenever I go completely wide open from idle, the engine sounds like it is flooding. This only lasts about a second, then it seems to recover and take off. The engine idles fine, and WOT is fine once I'm past the transition from idle, but that pause is irritating, not to mention I hate hesitations when I'm on the skiing end of the rope. I may be imagining things, but it seems more noticable after the boat has been idling for a few minutes, as I inevitably need to as I work with my kid.

I've searched on every related topic I can think of, but haven't found any identical issues. Does anyone have any suggestions? I'm thinking about looking into the IAC or MAP sensors next, but would appreciate advice from those of you who are already wise in the ways of Malibu. I've also heard that strange things happen as the coolant temp sensor goes bad, so I've got that on my list of options as well.

One last thing, I bought the boat in San Diego, and brought it back to Utah. I can't imagine why the elevation change would cause this issue in an EFI engine, but I'll just throw that out there.

Thanks in advance for any advice.

[mbaratelli]

I've been dealing with the same problem for the past 2 years and after raising hell with the service people, they finally called Indemar. The bogging is most likely being caused by a crack in your exhaust manifold. Don't run it until you've had it looked at. I haven't been given an estimate for the work but it's not cheap. Good luck.

[Rooster Tail]

New impeller is supposed to arrive today, so last night, under the cover of darkness, I pulled the impeller. Not pretty. I believe that for all practical purposes I have been spinning a finless rubber hub. As expected, most of the fins had found a new job plugging the tranny cooler. Got all of that cleaned out, and will flush the hoses before I put everything back together. I'm really hoping this solves the problem, but will post results. Planning on being on the water Thursday, so should know after then.

Thanks for the tip on the exhaust manifold. I'll check that also while I'm under there.

[Rooster Tail]

Took the boat out last night, and it runs like a champ. Occasional temperature surges into the 170 range, but for the most part it hovers right around 160. Throttle bog has disappeared, and I'm stoked! Love this boat.

Thanks to all for your help. May your lakes be smooth and your passes clean.

[Shine]

Took the boat out last night, and it runs like a champ. Occasional temperature surges into the 170 range, but for the most part it hovers right around 160. Throttle bog has disappeared, and I'm stoked! Love this boat.

Thanks to all for your help. May your lakes be smooth and your passes clean.

Excellent news, Glad you are back to Happiness!