Please don't tell me to search old post because I have...

Started getting 2 beeps per one sunny day. Had a buddy put it on the Merc code machine. No response from Idol air controller, TPS and low water pressure. I have replaced the IAC, TPS and the water pump. Still getting 2 beeps per and from time to time water pressure on the Merc machine drops, engine cuts out as if the fuel has been cut but doesn't shut off. Pressure got as low as 1.2 psi then builds back up to normal.

Today I checked voltage at the water pressure sensor...4.99 volts, removed it and installed a mechanical pressure meter with a hose long enough to watch while under way. When up on plane and running, always above 20 psi. and up to 30 at 50+ miles per hour. We ran for 10 or 15 mins at 3000 to 4000 rpm's. We had 2 beeps per mins from start up and through out the entire test run. I gradually increased to around 5000 rpm and got a solid beep but the engine did not cut back but I gradually reduced RMP's, around 3000 or so the solid beep stopped and returned to 2 beeps per. Never after getting on plane did water pressure on the mechanical meter drop below 20 psi.

Anyone have any thoughts?

Did You jump the switch at the connector so it thought you had water pressure? If not that's your solid probably, BUP should jump in soon he is the expert. But if you want to throw parts at it the Manifold temp sensors go a lot.

I think you have a couple problems unfortunately.

Are all of your IAC codes/alarms gone? The bad IAC can damage the harness and the actual PCM.

I also think you could have trouble with a temperature sensor, which is causing your engine to think it's overheating. Are you looking at Live Data on the scanner when running?

Interesting.. how do I do this?

We are looking at live data and so far the engine temp on the scanner matches the dash gauge. IAC code is gone and now appears fine.

This same thing happened to 2 boating buddies this year with the same 496 HO's

Jeff's was IAC failed. 2 beeps at low RPM, solid beep at speed. ( He replaced them on both engines then)

Steve's had a history code of cam sen (cam position sensor) giving him a beep randomly.

No matter what, if you have or had a beep, what caused it will be in the history when the computer is scanned

[QUOTE=Expensive Date;4339608]Did You jump the switch at the connector so it thought you had water pressure? If not that's your solid probably, BUP should jump in soon he is the expert. But if you want to throw parts at it the Manifold temp sensors go a lot.[/
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Correct, unplugging the sensor and not jumping the wiring connector should throw a seawater low psi hard fault and invoke a reduced power guardian condition. This will be logged and accessible in the fault history. Being that you are getting a two beep soft alarm, evidence should be in the active faults or freeze frame category. With the seawater psi sensor plugged back in, what % available power is there?

Unplug connector and use a jump wire on the pins.

Post your engine serial number of the engine unless you are all fixed up now. Missed this one and I am bored as hell today waiting for the weekend boaters to pick up their fixed boats.

Also anything new or what have you done since ? also is your app completely OEM stock with a stock PCM 555 ?