Wake 101
Home   Articles   Pics/Video   Gear   Wake 101   Events   Community   Forums   Classifieds   Contests   Shop   Search
WakeWorld Home
Email Password
Go Back   WakeWorld > Boats, Accessories & Tow Vehicles

Thread Tools Display Modes
Old     (Joregon)      Join Date: Oct 2016       06-21-2020, 11:57 AM Reply   
I have a 2004 centurion elite v with a MerCruiser 350 MAG EFI that is slow to start and when it does, the idle is around 500, even when cold. is this controlled by the IAC valve? seems like it should idle a bit higher to start and then idle down after warming up.

Anything else I should look into? I am unsure how idle is controlled otherwise.


Edit, I believe the previous owner replaced with a less expensive non-mercruiser part (automotive, not marine grade). not sure if that is pertinent but thought I would throw it out there.

Last edited by Joregon; 06-21-2020 at 12:02 PM.
Old     (GSXRcrasher)      Join Date: Jul 2013       06-24-2020, 11:08 AM Reply   
I have a 97 mercruiser black scorpion MPI 350 in my boat and a couple of years ago had problems with occasional hard starts and occasional loss of power. I replaced my distributor cap and that helped a bit but the main problem ended up being a bad fuel pressure regulator. The regulator was located pretty low near the back of the engine and a vacuum line had been knocked off of it at some point. Iím not sure if bilge water got in thru the vacuum line hole while the line was knocked off, but the regulator was still not working with the line re-attached. I replaced the regulator and that fixed my problems. Maybe check fuel your fuel pressure?
Old     (denverd1)      Join Date: May 2004 Location: Tyler       06-25-2020, 3:10 AM Reply   
does it start/run better when warm?

check diz cap, rotor, contacts in the cap. replace if it's been a while (several hundred hours)
check plugs for fouling
fuel pressure is a good one, could indicate a pump problem. hook up fuel pressure gauge to the fuel rail
Old     (TTyler89)      Join Date: Jun 2015       06-27-2020, 3:15 AM Reply   
My money is on the IAC. I don’t care how recent it was replaced, if it’s an automotive replacement it will not hold up to a marine environment. Distributor cap and rotor will smooth the motor up tremendously but not to the point that it won’t idle or start when cold. The idle is controlled by the ECU, it regulates idle with the IAC. More air it lets in higher the idle, and less air it lets in the lower the idle.

Last edited by TTyler89; 06-27-2020 at 3:21 AM.
Old     (TTyler89)      Join Date: Jun 2015       06-27-2020, 9:32 AM Reply   
Also if a cap and rotor and plugs haven’t been done for several years, I’d go ahead and do that as well. You’d be amazed at what a difference it makes in the way it runs. Since it’s a mercruiser, look on the big plastic breather cover for what spark plugs it calls for. Cross reference that over to ngk plugs and get those instead of the ac delcos. Also look for the plug gap on the breather cover and gap your new plugs to spec. If they are iridium or platinum plugs take care not to pry on the electrode when gapping as you will ruin them.


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

All times are GMT -7. The time now is 10:04 AM.

Home   Articles   Pics/Video   Gear   Wake 101   Events   Community   Forums   Classifieds   Contests   Shop   Search
Wake World Home


© 2019 eWake, Inc.    
Advertise    |    Contact    |    Terms of Use    |    Privacy Policy    |    Report Abuse    |    Conduct    |    About Us