Merc 5.0L will not idle

[Aerohokie]

I have about a 2005 Sea-Ray with 150 hours, SN 0W324202, Mercruiser 5.0L. When starting engine it will crank, fire, and immediately die. Only way to get it running is put it in Neutral at about 1000RPM and start. As soon as you go to idle it dies. I have a soft alarm for check engine with the 2 beeps every minutes. I pulled the foam out of the IAC, no difference. The water pressure was about 1 psi at 800 rpm or so and got to about 3 psi around 2600. Oil, temp all normal. Tomorrow I will get the codes pulled but does anyone have ideas for now?

-Dave

 

[Bifflefan]

Re: Merc 5.0L will not idle

im assuming its a carburated motor?
could be water in the gas, or carb
could be pluged idle air bypass' in the carb (needs rebuilt)
does it run good off idle?
might also be the idle screw backed off and just needs to be adjusted.

 

[Aerohokie]

Re: Merc 5.0L will not idle

im assuming its a carburated motor?
could be water in the gas, or carb
could be pluged idle air bypass' in the carb (needs rebuilt)
does it run good off idle?
might also be the idle screw backed off and just needs to be adjusted.

No it's fuel injected, MPI. I removed the foam for the IAC to make sure it wasn't plugged. It runs fine above 1500 rpm, slight slip here or there below that, dies under 600rpm. I think it has to be a sensor problem, but this is my first time working on a boat engine.

Oh yeah, there was a momentary fail on the oil pressure sensor and the gauge spiked, it displayed on the digital readout and then cleared. Oil looks/smells fine.

 

[Bifflefan]

Re: Merc 5.0L will not idle

Ok. i really have no experiance with that MPI. But i do have one for ya, NEVER run high octain Racing Gas of any kind in it. I did that in my truck and it cost 2000 to get all the injectors and hoses it ate replaced.

Sorry i couldnt help. Just an old Carb guy i guess.

 

[pdmathisjr]

Re: Merc 5.0L will not idle

Similar problem on 4.3... had to R&R IAC ($100 part).