I have 2007 mercruiser 496ho , when it s goes up to 3000rpm then get constant beep loose power if i stay at 1200rpm it is normal my temp is 170, oil pressure is 30psi. does anyone have this exper ,please help. thank you

Sounds like a saftey cut out problem see if this link helps:
http://www.michaelstractors.com/foru...?TOPIC_ID=199y

Don't guess, get the motor scanned.

If you plan on keeping that motor for awhile I would buy a scan tool of scan software. It WILL pay for itself.

http://www.rinda.com/marine/marine.htm

I must have said it a hundred times or more! If you own a 50-150 thousand dollar boat with Merc 496's, invest $30 in a number 30 service manual and PCM 555 diagnostics supplement and $400 in a hand held scanner from Rinda.
You can't guess a what's acting up on an electronic efi modern engine, nor can you waste money replacing parts that don't need replacing.
Hook up the scan tool, read the faults codes and fix the problem qucikly and efficiently!

Best Regards,
Ray @ Raylar

Thank s guys

i'm having beeping issues too, but no power cutout... haven't looked at temps/pressures as it's happening... I'll go buy a scanner.... but where the eff would i plug it in... i'm not a motorhead..... (clearly)

I justed bought scanner @ rinda.com it take about 5 days it s will come with instruction ,

There is a rectangular plug located on the top right hand side (facing motor), see pic.