496 mag ho alarm and hard cold start help??
 

Hey guys. Newbie to the board, but not to boats. Currently have a 2007 35 outlaw. Starboard engine is giving me trouble. When I start it it gives a hard coldstart and I must give it throttle to get the engine going. It then idles like crap for about 3 to 4 minutes before it will finally come out of it. Like it is only running on four cylinders or six. The two beep 60 second alarm then sounds the entire time it's running. But runs fine. Sometimes when I come down from running at cruising speed down to neutral that engine will also start to act up and sometimes stall. But as soon as I cycle the key on and off it will fire right back up without an issue and not run poorly. This makes me think it is a sensor issue not a mechanical issue where it comes out of it so quickly with the reset of the key.
Also if I give it full throttle sometimes I will get a solid alarm that will not shut off even when I throttle back down to idle. I have to again cycle the key to get it to stop sounding solid. As of now the 60 second beep is continuous all the time.

Help?
Very much appreciated.

Rick

Our previous race motor was a 496 Mag HO. It would beep and go into guardian mode from a bad electrical connection to a sensor. As far as DIY, I would check all the electrical plugs to sensors, clean them and add dielectric grease. Other than that, you need to plug into a Mercury diagnostic computer to find what is causing the code that trips the alarm.

You need to have it scanned. You can't just guess with these motors. www.rinda.com to buy your own scanner (priceless to have) or find someone who you can borrow one from.

Or you can take it in for service.

What you post sounds like a bad IAC, but I would not replace it without knowing the bad codes first. That's why the computer and beeps are there.

try swapping the fuel pump relay with the other engine

IAC on the throttle body is bad that's the hard start and bad idle, but that isn't hooked to the alarm.