5.7L Merc starting issue

[KMK0404]

I have a 2000 Rinker 270 cruiser with the 5.7 EFI motor in it and recently came across some issues. Ive never had to do this before in the 16 years ive had the boat but now when I turn the key the engine requires some throttle to start and then once it runs for 30sec I can back the throttle down to Neutral and it runs fine. Any idea as to what this may be? Engine got new plugs and wires last fall as well as fresh oil and fuel.
thanks

 

[johnnygjr]

high hours on engine? look down throat of carb have asst. move throttle see if accelerator pump sends fuel to intake manifold. Check compression in cylinders possible low vacuum.Check all vacuum lines,cracks, breaks. Fuel issues, stale fuel from last fall !!!ethanol.

 

[fastjeff]

Sounds like the device to increase idle speed when cold (IAC?) is messed up.

Jeff

 

[Docksidemarineservices]

Sounds like the device to increase idle speed when cold (IAC?) is messed up.

Jeff

Definitely the Idle Air Control(IAC).

Post the serial number for the correct part number.

 

[KMK0404]

Thanks for the responses. How would i test or check the IAC to see if its bad?

 

[Docksidemarineservices]

Thanks for the responses. How would i test or check the IAC to see if its bad?

With out CDS to check it, purchase one and install it.