Throttle Lever Buzzing

Got the boat out for first time this year over the holiday weekend. First day on lake was great, did a little surfing, water still a little cold for my liking but manageable. Second day (next day) was just as good but about 45 minutes to an hour in the throttle lever started making a loud buzzing noise kind of like an electric razor my wife says, but to me sounded like an alarm of some kind. Looked behind the wall were throttle is mounted and see a couple wires connected to it. Couldn’t figure out what the noise was so shut the boat off and the noise continued for probably another minute or two, then the noise just stopped. Fired boat back up and no issues rest of day or the following day. From looking on the web stumbled across a thread about an older (70’s) boat, outboard engine of some sort were people responded to a similar question saying it was an alarm that sounded when engine was possibly running hot. Has anyone experienced this with the moomba or have any thoughts on what the noise may have been from/for? I had the water pump impeller replace the day before first day of use, related possibly? Thoughts?

Quote:

---

Originally Posted by Seahawk

Got the boat out for first time this year over the holiday weekend. First day on lake was great, did a little surfing, water still a little cold for my liking but manageable. Second day (next day) was just as good but about 45 minutes to an hour in the throttle lever started making a loud buzzing noise kind of like an electric razor my wife says, but to me sounded like an alarm of some kind. Looked behind the wall were throttle is mounted and see a couple wires connected to it. Couldn’t figure out what the noise was so shut the boat off and the noise continued for probably another minute or two, then the noise just stopped. Fired boat back up and no issues rest of day or the following day. From looking on the web stumbled across a thread about an older (70’s) boat, outboard engine of some sort were people responded to a similar question saying it was an alarm that sounded when engine was possibly running hot. Has anyone experienced this with the moomba or have any thoughts on what the noise may have been from/for? I had the water pump impeller replace the day before first day of use, related possibly? Thoughts?

---

How long have you not serviced the engine? This may cause the machine to make an unpleasant noise. wordle game

Your 2018 Mondo should not buzz....it will be an audible beep if there is a fault amd the amber check engine light will be on.
The screen will show codes and you can check. Example SPR-3712 FR1

Any buzzing noise is probably a loose bolt or something behind the wall the throttle is mounted to. I would be cautious putting your head down there if your boat sits out. Many critters find that space behind the throttle wall as a good nesting area.

Other buzzing sources could be electrical. Stereo distorition, bad ground, loose connection will all create feedback that you can hear through speakers even if volume levels are low, but this would go away once the stereonis powered down.

As for overheating, your boat has 2 alarms before bad things happen. 1. Water not flowing = sensor in cooling water not seeing flow or bad sensor. 2. High temp warning
The screen should show engine data in the menu and you can monitor that also. Normal is 165*F but under high loads I have seen 180*F.....engine will take 210*F without an issue but I would shutdown at that point and start checking the fresh water cooling loop. The engine is closed loop and has its own antifreeze. If you have a heater.....they are known to leak slowly and you could be low on coolant. Again you would get an alarm once you started to over heat.

Julia - Engine is serviced, fluids changed every year when winterized. Impeller changed at beginning of year so it does not sit all winter.

Holdmybeer – agree should not buzz. Check engine light never came on and temp gauge sits right around 160-162 consistently. Screen also showed no codes. Buzz probably not the right word to describe but sounded like an audible alarm of some sort that was not wavering, beeping etc., just a solid noise for about 2-3 minutes. Lasted even when turning the key to the off position. Then stopped after a minute or so when the key was placed in off position. Not worried about critters (Garage kept and covered all winter long, very detailed/cleaned year-round) right next to my car. I was thinking possible stereo feedback from improper ground, etc. that may have wiggled loose (JL Audio MX500/1 amp to run sub). This could be the case as my sub amp started going into safe mode for some reason the day before and early this day that the noise started. Amp fine when just sitting or cruising at low speed but when speed picks up or bouncing due to waves it goes into protection mode. Thought amp may be overheating to cause protection mode but just warm to touch.
When noise started it actually took me a bit to locate where it was coming from which led me to the back of throttle area but was still difficult to tell for sure as I think it was echoing throughout the driver’s area (SUB mounted at drivers feet like most) but sure seemed like it was coming from behind the wall the throttle is mounted to. Do you know if there is an audible alarm in the engine bay? Maybe it was just traveling down the inner wall of boat. Guess I will start by figuring out the amp issue. Maybe a good opportunity to upgrade amp and add another sub or two ��.

Thanks for the responses, just trying to find a starting place. Noise did not occur again after the initial one occurred nor any issues the following day other than amp kept going into protection mode. Have to power off head unit to get amp to go out of protection mode.

You have a loose or missing ground.

Under the dash look up and you will see 2 buss bars 1 for power 1 for ground. The noise sounds like the system is grounding through the horn and creatng a light hum alarm sound. The horn could even be shorted from water (I doubt that though). The horn sits in front of the sub wall under the dash on the starboard side. It would easily echo down that wall. Also check the buss bars by you amp under the port locker. Check the starter connections and engine ground strap.

Even though you treat your boat like a baby (self included) I have found loose screws and bolts all the time. That JL amp is nice and is going into protection because it doesn't have proper ground. Engine speed causes the vibration wire looses strong ground goes into protection.

Holdmybeer,

Wanted to follow up with you now that I was able to get a test run in this past weekend, thanks for your input, issue resolved. Here is what I found. All connections at buss bar were solid. Checked all other wiring under dash and at battery (all good). Removed amp mounding board to see amp connection/wiring that were hidden. When looking I noticed the butt splice connectors for the grounds coming from 2 of my amps were crimped to much (little tear) which exposed the metal inside them. Both grounds were close to each other so thinking they were wiggling when in motion which was just enough to cause one amp to go into protection mode. Fixed connections and had no issues with the sub amp going into protection mode this weekend. Also hit the horn button while on the lake (first time ever hearing the horn). That was extremely like the alarm/noise I was trying to describe, just not near as loud as the horn itself, but a faint replication of the horn so think you were correct that the faulty ground might have been affecting the horn as well. Appreciate your response, as it assisted in determining a place to start trouble shooting!

Great to hear!

Yeah the horns are weaknon these boats but you described the sound that was the first thing I thought of.
Good to know the amps and back up and running also.

The horn!! Good lord why did Moomba put the scooter horn on these boats? It just destroyed my ego the first time I hit that thing out on the lake![emoji23]

Sent from my SM-G781V using Tapatalk

I thought they were bad at first too, but they seem very directed. When I bounced it off a canyon wall it was very clear above the sound of the engine.