1989 mercruiser 3.0l idle question...

[ArkBoater]

Hey gang. Simple question here and I hope ya'll can give me a simple answer. My boat has the motor mentioned in the title, I have to give it about 1/2 throttle to start then when at idle, it will not die, but it runs really rough. Sounds about like a motorcycle engine running if you know what I'm saying. ha Anyway as soon as I kick it in gear, it runs as smooth as anything. Any ideas here? I'm not great with engines seeing as how this is my first boat so more details would be great when you give an possible fix. :redface: Do I need to adjust the idle? If so, how is that done? Thanks!

 

[chiefalen]

Re: 1989 mercruiser 3.0l idle question...

Heres a link to starting a carbed motor. You can find all kinds of good stuff at the top of the forum " Adults only " including a manual for your motor and drive. What does it idle at in gear in the water?

http://forums.iboats.com/showthread.php?t=279911

 

[ArkBoater]

Re: 1989 mercruiser 3.0l idle question...

Heres a link to starting a carbed motor. You can find all kinds of good stuff at the top of the forum " Adults only " including a manual for your motor and drive. What does it idle at in gear in the water?

http://forums.iboats.com/showthread.php?t=279911

I don't have a problem starting the boat. (I just throttle up a little and it will start fine) Its the idle I'm asking about. Anyone have any suggestions for how to fix my idle problem? Thanks

 

[chiefalen]

Re: 1989 mercruiser 3.0l idle question...

All carbed motors for the first 5 minutes or so will run real rough till the choke opens all the way. Does the choke open all the way after 5 minutes or so?

After warm what does it idle at ??

 

[ArkBoater]

Re: 1989 mercruiser 3.0l idle question...

All carbed motors for the first 5 minutes or so will run real rough till the choke opens all the way. Does the choke open all the way after 5 minutes or so?

After warm what does it idle at ??

I am really not sure what it idles at. :redface: It should be around 800 right? It seems to idle rough no matter if it's warm or not. Its right at the point of dying but it doesn't. But as soon as I shift it in gear, it's smooth. Does it sound like adjusting the idle would fix it to you? I'll have to hook up the muffs and check the RPMs at idle.

 

[chiefalen]

Re: 1989 mercruiser 3.0l idle question...

Your idle is to high. My opinion you need to rebuild the carb. and set it up correctly.

Clean the filter at the fitting that enters the carb. You have a fuel water separator? Dump it in a clean clear container and let it sit, what do you see.

Go to the top of the forum " Adults only " And d/l the manual.

You can thank Don s for posting that invaluable resource, it has saved people alot of money.

 

[180shabah]

Re: 1989 mercruiser 3.0l idle question...

You can't properly adjust the idle on muffs. It needs to be in gear in the water and the engine needs to be fully warmed up with choke open. The set to specs in the manual - probably 600-650rpm.

 

[JustJason]

Re: 1989 mercruiser 3.0l idle question...

when was the last time the motor had a full tune up?

 

[ArkBoater]

Re: 1989 mercruiser 3.0l idle question...

Not sure of the last tune up.

But anyway, I didn't say mine was idling at 800, I was asking if that was what it should be at. (read my post again.) And thanks for the heads up on adjusting stuff on the muff. I just bought the muffs a couple weeks ago so I haven't had them on there yet.

 

[Don S]

Re: 1989 mercruiser 3.0l idle question...

800 rpm idle is to fast. Usually the 3.0L engines have to be below 750 rpm. Main reason is to prevent them from dieseling (run on) after you shut them off.
Adjusting the idle mixture and idle speed can be done on muffs, but it's a lot closer if rechecked and adjusted in the water.
But all the carb adjustment in the world is kind of useless if the plugs and points are shot or the timing and dwell is off, or the compression is out of spec.
It all has to be set up at the same time for best results.

 

[Bondo]

Re: 1989 mercruiser 3.0l idle question...

But all the carb adjustment in the world is kind of useless if the plugs and points are shot or the timing and dwell is off, or the compression is out of spec.
It all has to be set up at the same time for best results.

Ayuh,.... A Tune-Up......

 

[ArkBoater]

Re: 1989 mercruiser 3.0l idle question...

800 rpm idle is to fast. Usually the 3.0L engines have to be below 750 rpm. Main reason is to prevent them from dieseling (run on) after you shut them off.
Adjusting the idle mixture and idle speed can be done on muffs, but it's a lot closer if rechecked and adjusted in the water.
But all the carb adjustment in the world is kind of useless if the plugs and points are shot or the timing and dwell is off, or the compression is out of spec.
It all has to be set up at the same time for best results.

I just replaced all the spark plugs before last summers boating season (they were bad) so they are good now. I need to get it tuned up I guess. That's something I will have to have done though because my knowledge isn't deep enough to tackle that. Thanks for all the info guys!

I know you won't know close numbers, but ballpark what can I expect to pay for a good tune-up (figuring nothing major is wrong)? I just want to know so I don't get screwed. ha :redface: Thanks again.