Ignition alarm

[samw]

2000 merc 315 hp, 160 give or take

I've seen mine touch 170 once but usually hoovers around 150-160.

I just had my running in the drive way. At idle with a hose my ran at 170-175. On the lake is more around the 160-165 mark.

[ctcranor]

hubdawg-

Is the blue wire the wire that attaches to the knock sensor? Just curious, I haven't picked it back up yet so I don't know what they found. I did ask them to change the impeller even with my low hours. I think I'll just do it every other year from here on out.

[talltigeguy]

hubdawg-

Is the blue wire the wire that attaches to the knock sensor? Just curious, I haven't picked it back up yet so I don't know what they found. I did ask them to change the impeller even with my low hours. I think I'll just do it every other year from here on out.

I think that is very wise.

Yes, the blue wire is the knock sensor and attaches to that plug right there.

[chpthril]

hubdawg-

Is the blue wire the wire that attaches to the knock sensor? Just curious, I haven't picked it back up yet so I don't know what they found. I did ask them to change the impeller even with my low hours. I think I'll just do it every other year from here on out.

It's best to change it in the Spring when you summerize and not having it sit 5-6 months unused installed the housing at winterizing.

[hubdawg]

The blue wire connects to the knock sensor which is removed for winterization.

[LakeBum22]

ignition alarm

I am pretty certain that the alarm is tied to (among other things) the v-drive oil pressure. You won't see it on any gages like you would with the engine oil or the water temp but you should have a trans oil light on the top of your dash. It is normally on when the boat is idleing or in gear but as soon as you start to throttle up it should shut off. If this light was coming on while the alarm was going off then I would check to make sure you have the proper fluid level in the v drive. Don't mistake the trans oil light for the transmission. I am pretty sure it tied directly to the V-drive oil pressure sensor. I had a similar problem but instead of the sound alarm going off the light was coming on. I just needed a new sensor.

[R&T Babich]

I am pretty certain that the alarm is tied to (among other things) the v-drive oil pressure. You won't see it on any gages like you would with the engine oil or the water temp but you should have a trans oil light on the top of your dash. It is normally on when the boat is idleing or in gear but as soon as you start to throttle up it should shut off. If this light was coming on while the alarm was going off then I would check to make sure you have the proper fluid level in the v drive. Don't mistake the trans oil light for the transmission. I am pretty sure it tied directly to the V-drive oil pressure sensor. I had a similar problem but instead of the sound alarm going off the light was coming on. I just needed a new sensor.

The "Trans" light on the dash of our boat is for the pressure sensor on the Walter V-drive and not the Borg Warner Velvet Drive transmission. It is a 2 psi Hobbs Corp. - 76061 normally closed switch that will open to turn off the dash light when the RPMs are increased above idle. According to the 1999 Mag MPI wiring diagram it is not an input to the computer so would not set off the alarm. I just checked the Merc website for the drawings and it looks like the drawings are no longer available. Apparently Merc is no longer supporting engines made before 2000 on the website. Fortunately, I downloaded all the drawings/parts lists last year and found them hiding on a backup drive. If anyone needs a copy of the gifs for a 1999 Mag MPI I'll pass them along.

[ctcranor]

Cause Found

The blue knock sensor wire had fallen off the knock sensor. I'm glad it was simple and now know what to look for if it happens again.

Thanks for everyone's input! Got that impeller changed out just to be safe. The original was in great condition so I have it in the glove box incase one ever fails while on the water.

[Escondido]

I had a similar issue this weekend. Running at a low speed, 10-15 mph, light came on and alarm sounded. I also lost power. Boat idled fine but power was lost. Turned off the engine and restarted and alarm vanished and boat ran fine. I started heading back to the dock in the 20's, similar thing happened. This time when I took off it almost felt like the prop slipped. Reversed just to make sure nothing was hung up on the rudder, and started off just fine. No other alarms after that. All gauges normal. This is a 22ve, 5.7L engine.

Any ideas? I did not check the vdrive fluid level. Does it get low without a leak?

[dogbert]

Sounds like it's not getting enough fuel. When was the last time you changed fuel filter?

[Escondido]

Changed late last season. Would that cause the alarm to sound and vdrive light to come on or just the loss of power?

Maybe I just picked up some trash in the fuel that had to clear.

[dmgski22ve]

Mine had a MAPS (Marine Air Pressure Sensor) go out and it would come on after I had it warmed up and had been riding for about an hour... We tried replacing everything from impeller to throttle to knock sensor, etc...