2004 w/ twin 496's I start the boat and after it warms up two beeps every minute.
drive fluid full
antifreeze good /water temp good
oil preasure good
water preasure good
What could it be!!!!!!!!!!!!!!!!!Then if I take a ride for ten minutes over 4000rpm the hard alarm goes off untill I slow down.then the two beeps go again.

take it to get scanned??

And when you get it scanned if there are no codes let it run and watch the idle counts. If it doesn't drop down to 40-50 after a minute or two you have a bad Idle Air control.

On my HO, I've had three things cause alarms so far, first time I just needed to flush the heat exchanger out, just sucked up a little sand and I wasn't getting good water flow

Second, my IAC valve went bad, it was about 90 bucks for a new on, also the engine wouldn't idle and was stalling alot. Thats on the top rear of the intake manifold.

And last was my water pressure sensor, when it went it was intermittent at first then I couldn't even get the boat to plane, it reduced the engine to 20% power by 1800rpm. That was 85 bucks, not to bad, that sensor is on the first cooler the sea water hits on the back of the engine near the transom assembly...

I had the same problem. Very frustrating. Turned out to be sand/debris scoring in sea water pump housings. Expensive, but did the trick.

Sonic,

Do you have a smartcraft monitor? If not, I highly recommend one. You'll get real time engine info including alarm codes. Plus all the other benefits like fuel burn, etc. Get a Northstar unit and you can have GPS too.

With the Smartcraft you'll be able to immediate feedback on all of those 496 alarms you seem to be plagued with. Plus, you will get more accurate engine data as compared to the the analog gauges.

Just a thought.
Techman

thanks guys i will have a friend scan it tuesday.Just to let you know The heat exchangers were both taken off this past winter to preasure check I did have a leak and replaced one.

Had e same issue. Mine was the water pressure sensor as well. 110 bucks and done..........hours of pulling my hair out though

Where is the best place to buy one?

I am having all kinds of alarm issues as well with my 496. Had it scanned and the codes were for low block pressure. Also showed an overheat of 190 degress about the same time. Pulled impeller out (I freaking hate that job) only to find impeller is good. I back flushed the hoses and found no debris. So I am at a loss right now.

I too am looking to install a smartcraft gauge in my boat. I found the SC1000 in white and black on ebay for around $188 new. It only comes with a 3' cable so I am still looking for the extension cable to run it back to the harness on the motor..... SInce my the Drivers dash is full, I am going to mount the Smartcraft Gauge on the passanger side. The Velocity has a Gauge Blank on the Pass. Dash. Thats the only place I have.....