240 EFI M2 odd beeping as engine briefly stalls

[mykelbutler007]

Hi, Engine starts off fine. As the engine idles, the Rpm's drop from 2000 to 1500, or lets say a drop of 5000rpm. As this happens the warning horn beeps in unison with the engine drop. Boat runs, and at WOT has same drop / stall/ engine horn. Replaced water seperator, new plugs, new temp sensor (1) of 2, still cannot solve issue. Thinking electrical, but the manual doesn't have a solution for an intermittent beep associated with a temporarily power loss.

 

[Dr Honda]

OK... so it's ok at low RPM, and drops at high RPM?

I know you said you replaced the water separator... but did you change the small filter at the lift pump?

Since you have a 2006 boat... I will assume it's a gen2 engine. Since it probably is... and since it's a "Smart" system... have you hooked a scan tool to the computer to see what the error was?

 

[mykelbutler007]

My apologies, the Drop is 500 rpm, not 5000. I was not aware of the small filter, and really do not know what it looks like. Come to think if it, the symptoms did start after the water fuel separator replacement. The problem is really intermittent, happens more at idle and not in the mid range, but under high load. So basically low and high load. Leaning towards electrical since most of the wires started to corrode b/c of saltwater.

 

[mykelbutler007]

 

[mykelbutler007]

Just took the boat out today and saw the Voltage linger around 10amps, even under hard acceleration. Can I safely assume that this mysterious issue is a result of a poor or not working alternator?

 

[Tim75]

You are mixing units- a little confusing.
Are you measuring VOLTS or AMPS?

 

[mykelbutler007]

Sorry Volts

 

[mykelbutler007]

Have not hooked a scan tool to boat yet, want to order one, but the ones I found are around $200plus

 

[Dr Honda]

you found a $200 tool?? WHERE !!!! The cheapest one that I've found, that can talk to the Merc engines we have is closer to $500.

If the voltage won't come up above 10v... then I'm pointing my finger at your alternator. These engines like to be above 11v, but prefer to be around 13v while running.

 

[mykelbutler007]

Problem solved after countless replacement parts. Good thing is that the boat should be solid for many years. Autozone offered me replacement spark plugs for the NGK ones. They were Champion Y(something). The plugs were causing the misfire and drop in rpm's. Don't know why. I ordered NGK's, placed them in and the boat purrs, well roars like a kitten. Time for me to actually enjoy the miami sun now.

 

[SeptemberC]

Definitely can not use other spark plugs. Always stick to the NGK’s. They are special and don’t interfere with the electronics on the marine engine.
In an emergency we attempted to use a non NGK and it wouldn’t run hardly at all and then blew a fuse at the engine. Lesson learned.
Glad you found out what the problem was.

Problem solved after countless replacement parts. Good thing is that the boat should be solid for many years. Autozone offered me replacement spark plugs for the NGK ones. They were Champion Y(something). The plugs were causing the misfire and drop in rpm's. Don't know why. I ordered NGK's, placed them in and the boat purrs, well roars like a kitten. Time for me to actually enjoy the miami sun now.