# Mercury O/B idle to high



## WhyMe (Apr 21, 2013)

In the past two weeks that I have been out, I have noticed that my outboard is idling too high ( 1100 rpms). The decal on the engine says not to put in gear over 750 rpms. I researched on the net to idle down the engine, but found nothing. I really don't want to take it to the mechanic for a simple turn of a screw. Any help on this matter (input), or take a few moments to look at the engine would be greatly appreciated. 
Thx Whyme

Engine is Mercury 225 offshore.


----------



## WhyMe (Apr 21, 2013)

Another pix.
Whyme


----------



## Sequoiha (Sep 28, 2007)

It's not a simple turn of a screw, when a fuel injected motor idles high, something is telling it to. If it just started, it's probably a vacuum leak, recirc tube leak, or something like that, maybe a coolant temp sensor telling the ECM it's cold, probably need to let a tech look at it,


----------



## billfish (Feb 23, 2016)

on the verado that is a throttle body in the front of the engine, metal flange with rubber boot, the boot starts to come lose and lets it draw air causing hi rpms, not sure if your motor has something like that


----------



## Sequoiha (Sep 28, 2007)

His is not a Verado, it is a 225 offshore EFI, but you are correct, if the isolater boots becomes delaminated it will introduce uncontrolled air, (aka) vacuum leak and cause a high idle.


----------



## WhyMe (Apr 21, 2013)

Thanks for the input. If it stops raining, I'll take a closer look at the engine and the hoses.
Whyme


----------



## WhyMe (Apr 21, 2013)

I found what might be causing the problem. I found this hose hanging on by a thread and it looks to be dry rotten. If the engine was running , the nipple would be sucking air. 
Whyme


----------



## off route II (Sep 28, 2007)

billfish said:


> on the verado that is a throttle body in the front of the engine, metal flange with rubber boot, the boot starts to come lose and lets it draw air causing hi rpms, not sure if your motor has something like that


just went through this exact scenario with mine.


----------



## WhyMe (Apr 21, 2013)

Bad news. I replaced the hose and I'm still getting the same results ( 1100 rpms) . :-(.
Whyme


----------



## lastcast (Oct 12, 2007)

Try spraying ether around the air intakes and vacuum lines.


----------



## rscrubberrn (Apr 24, 2015)

I had the same problem with my Suzuki it turned out being a blown intake manifold gasket. I ended up taking it to the shop after spending a lot of time messing with it on my own. Was well worth taking it in.


----------



## WhyMe (Apr 21, 2013)

Thanks for the feedback again. I think it might be in my best interest to send my baby off to get fixed. I'll call this Monday to set up a time. 
Whyme


----------

