Inconsistent idle 3.0L

[Jmunk]

Ever since I've owned my current boat (98 Searay 180 with 3.0L) I have had an inconsistent idle issue. If I set the idle speed to 650-700rpm in forward gear idle it is good. After I run at higher RPM and slow down and put it in neutral it will hang around 900rpm, then drop to 800 rpm after 20 to 30 seconds. I'm stuck on why it doesn't return back to the 650-700rpm.

I double checked the float height, it's spot on. I checked the throttle cable and it's not too tight, and it has slight pressure pushing the butterfly closed. The concern that I have is after I pull a skier or a tube it will idle at the 900 to 800rpm and I just don't like to engage the drive at that rpm. Any thoughts of what to try ? I have reused the airhorn gasket twice now, possible vacuum leak ?

 

[Don S]

Re: Inconsistent idle 3.0L

Possibly the throttle cable is a little sticky or worn a bit and has a little more slop than new. May just need to adjust it.
Disconnect the throttle cable from the carb linkage, and adjust the cable barrel so the is just a little pressure on the throttle linkage to bring it back to idle. Not so much pressure that it forces the linkage, just a little pressure.

 

[palace]

Re: Inconsistent idle 3.0L

This is merc? I am reading on changing my shift cable on my OMC 3.0 and there is one of the 2 switches on the shift cable bracket, interrupter switch and overstroke switch. Interrupter should lower rpms when going into gear. I am not sure if Merc. has these. It makes sense to have. Find where this switch or similar system is and check it. Anyone else?

Ever since I've owned my current boat (98 Searay 180 with 3.0L) I have had an inconsistent idle issue. If I set the idle speed to 650-700rpm in forward gear idle it is good. After I run at higher RPM and slow down and put it in neutral it will hang around 900rpm, then drop to 800 rpm after 20 to 30 seconds. I'm stuck on why it doesn't return back to the 650-700rpm.

I double checked the float height, it's spot on. I checked the throttle cable and it's not too tight, and it has slight pressure pushing the butterfly closed. The concern that I have is after I pull a skier or a tube it will idle at the 900 to 800rpm and I just don't like to engage the drive at that rpm. Any thoughts of what to try ? I have reused the airhorn gasket twice now, possible vacuum leak ?

 

[Don S]

Re: Inconsistent idle 3.0L

This is merc? I am reading on changing my shift cable on my OMC 3.0 and there is one of the 2 switches on the shift cable bracket, interrupter switch and overstroke switch. Interrupter should lower rpms when going into gear. I am not sure if Merc. has these. It makes sense to have. Find where this switch or similar system is and check it. Anyone else?

Huh


Not sure what you are talking about. But if you are trying to ask a question, you need to start a new thread of your own, over in the OMC forum. This thread is about idle speed, not omc cable adjusment :facepalm:

 

[Jmunk]

Re: Inconsistent idle 3.0L

Don,

I checked the tension of the throttle cable and you were right, it was preloaded tight and maybe it possibly was binding the linkage. Have to wait and see if I go out tomorrow if it helps. Thanks.

 

[Jmunk]

Re: Inconsistent idle 3.0L

Went out today and idle was still pretty much the same as posted earlier. I'm puzzled as what to try next

 

[Jmunk]

Re: Inconsistent idle 3.0L

Last time I have the boat out I did a lot of adjustment in terms of the idle speed and idle mixture to try to get a consistent idle when I come off plane. I didn't have any luck, seemed no matter what I did it still would hand around 1000-900rpm for about a minute then slowly climb down to 800rpm and sometimes it wouldn't come down much. When it was hanging around the 1000-900rpm right when I came off plane, if I put it in gear (I know it's too high) then put it into neutral it would near the 750-800 I set it too.

Also not sure if it's related or not, but once I set it to where I liked it to idle at and shut it off and went to turn it back on in 15min or so it would start with no throttle input, but would idle around 500-600rpm and would be rough. If I give it some gas in "throttle only mode" it would be fine when I let it return to idle, this has pretty much always been the case since I've had the boat. I'm not sure if I need to adjust the float or whats going on here. Ideas ?

On the throttle cable it seems that the end that attaches to the carb linkage can slide on the carb linkage stud side to side about 3/16, is that normal or should there be a spacer of washer on the stud besides just the nut on the end? I will turn the barrel on the throttle cable out one more turn and see if that has any effect, not sure if its still to tight.