92 Merc 3.0L Idle Question

[SteveRay]

I started the engine after sitting all winter and I noticed that the idle was at about 900 rpm's and I though it was a little high. I read some of my Seloc manual but I still have some questions. The main question being:<br />What is the difference betweeen the idle set screw and the idle mixture needle and what are they used for and when?<br />Thanks in advance AGAIN. You guys always save me!

 

[SteveRay]

Re: 92 Merc 3.0L Idle Question

Someone please!!!!!

 

[Bondo]

Re: 92 Merc 3.0L Idle Question

What is the difference betweeen the idle set screw and the idle mixture needle and what are they used for and when?

"the idle set screw" sets the Idle Speed........<br />"the idle mixture needle" determines the air to fuel ratio.............<br /><br />If I've got to answer the rest of your Question,...........<br />You're Not Qualified to have Your fingers Anywhere Near the Engine..........

 

[Don S]

Re: 92 Merc 3.0L Idle Question

You don't know how to check oil, and you want to adjust a carb???? I'm with Bondo, at this point, you shouldn't even be messing with your boat.<br />First things first.<br /> Click Here

 

[trog100]

Re: 92 Merc 3.0L Idle Question

he aint asking any super duper how do i strip my drive type questions now is he.. just making sure he has his oil level right.. now he wants to know how to slow his engine down a bit..<br /><br />the mixture screw adjusts the fuel/air mixture the engine is getting when its at idle.. no need to fiddle with that..<br /><br />the throttle stop screw.. that does pretty much what it says.. it stops the throttle butterfly from closing too much and is what keeps the engine going as opposed to it just stopping when the throttle is closed..<br /><br />if your engine is idling at 900 rpm.. u screw the throttle stop screw in a bit (1/4 turn) and the throttle butterfly closes a bit more and the engine idles slower<br /><br />screw it in too far and will come to a stop.. if u have a good look at were the throttle linkage joins the carb it should be apparent which is the throttle stop screw..<br /><br />and if u have picked up and fully understood these two points u aint doing bad.. u know about as much as the average dude does about how an engine works.. a few more sensible questions and u will know a damn sight more than most.. he he he<br /><br />trog100

 

[Don S]

Re: 92 Merc 3.0L Idle Question

No trog, he needs to get a manual and study it for a bit before he goes playing with his engine and drive because his boat is nothing more than a toy to many people. Not necessarily to SRS, but there are lots of people out there that think that there is a "push this button" type fix for everything on a boat. They would even think of raising the hood on their car, but since the boat is a toy, lets go for it....... Bull Hockey. Messing with the fuel system without knowing what you are doing (even slightly) is dangerous. <br />Getting the manual and reading and studying it will help in his knowledge of things, but trying to through bits of information at him and expecting him to understand it is crazy. He doesn't even understand how to fill his engine with oil or why !!!!!<br />Quit trying to go against everything that everyone else says on this board. It doesn't even matter, fuel tanks, battery cables, carbs, your dangerous "DUDE" since you like that word. Give it a break and quit trying to over or under do every damn post on this board.

 

[trog100]

Re: 92 Merc 3.0L Idle Question

no rocket science in giving a little screw a little turn assuming u know exactly what it does.. i have explained exactly what it does.. i see no problem.. only the ones u choose to make..<br /><br />u give him your advicee don let me give him mine.. and if the only answer guys like steve are gonna get to simple questions is "buy a manual".. what on earth is this forum for..???<br /><br />and don.. if i may be blunt (only cos u have) your original answer to steve was both ignorant and insulting..<br /><br />get off by back dude i cant be doing with it..<br /><br />i end this one here and aint gonna get dragged into any more sily arguements.. okay<br /><br />trog100

 

[Don S]

Re: 92 Merc 3.0L Idle Question

get off by back dude i cant be doing with it..<br />

You better be "Doing with it" dude, you're the one on everyone elses back.<br />Sorry you can't handle the concept that not everyone is mechancially inclined, but they are not.<br />Most didn't come here to find out how to fix anyting, they just wanted to know the magic button to push. So you go with your trog theories, of boats, cause I am really tired of you and the fight it takes for people to find out the proper way to fix things. It can now be the "Trog site of boat theory and repair" cause you ain't gonna see me on this site again.<br />I'm just really sick of all your bull sheet.

 

[SteveRay]

Re: 92 Merc 3.0L Idle Question

First of all guys I did not want to start some kind of battle. Let me clear a few things up!<br />1. I do have a manual, both a paperback Seloc and access to the Merc one online. <br />2. I did read the manual but wasn't sure if I needed to actually do the entire process of putting the boat in the water, tying it off, putting it in gear etc. <br />3. I know how and why to change oil Don. <br />I post some questions here for clarification and reassurance. Sometimes you guys clear things up or have some sorts of tricks or insight due to your vast experience over others. I was simply looking for a clarification is all. Did not want to create a battle or have people flaming my post and I appologize that it got this far. <br />I guess my last question (I did check the manual for this but did not see it) What is idle speed supposed to be in gear?

 

[trog100]

Re: 92 Merc 3.0L Idle Question

its the in-gear.. boat in the water... idle speed thats critical steve.. <br /><br />under no load and with the engine exhaust out of water such as in your driveway.. the engine will idle a little higher than when its in the water.. the exhaust having to exit below the waterline causes back-pressure which slows it down some.. <br /><br />also when u drop it into gear there will be another slow down.. basically it all wants setting up to be as low as it can be consistant with it running reliably while in gear.. <br /><br />600 rpm while in gear should be something to aim at.. the bottom line being does it run reliably at this speed while in gear.. it should do if everything is well..<br /><br />so.. an example 800-ish rpm in the drive.. this could drop to 700-ish with the boat in the water.. this again could drop to 600-ish when place into gear..<br /><br />this is an example.. in reality the differences between the three idle speed situations can vary.. so there is no exact figures.. to get it right the final throttle stop screw tweakings need doing with the boat in the water..<br /><br />the bottom line.. it doesnt want to be idling any faster than it has to.. and it dont wont to stall out and stop when u put it in gear.. <br /><br />its the silly old clunky dog-clutch that is the reason for getting the idle down as low as u can.. going into gear at too high an idle rpm dont do em any good.. <br /><br />trog100

 

[craze1cars]

Re: 92 Merc 3.0L Idle Question

Whatever happened to "if you don't have anything nice to say...don't say anything at all?" The snide remarks and the following battle on this post are sad, IMO.<br /><br />If you have the original flame arrestor cover on the motor, your idle speed spec is possibly printed right there along with your max RPM range. But maybe not...gotta go to the garage and look at mine to see if that's true. Anyway, I also have a 1992 3.0 and just went through a full tune-up and had to find the same info out for myself...If memory serves me right, should be in the 650 to 750 range. I'm sure it's also in your Seloc manual somewhere, probably in some "specifications" pages. Just read a little further and you'll find it for sure.<br /><br />I also did discover that my RPMS drop a bit in the water. If it idles at 650 in your driveway, it'll likely stall in the water. Like Trog says, it's supposed to be done in the water, in gear. Takes 2 minutes to adjust. Check it next time you're floating and you have someone to steer and look out for ya while your head is "under the hood."

 

[tommays]

Re: 92 Merc 3.0L Idle Question

craze <br /><br />i try to never insult anybody but sometimes you have to save people from them selfs<br /><br /><br />after you read a few posts about people doing things like testing there electric fuel pump by letting it pour gas all the engine bay or pulling live live wires off the starter <br /><br />you will find that at some point your going to say to someone if you dont understand how to do something after reading the manual then your not ready to take on that repiar just yet<br /><br />getting the idle right on a 3.0 is way harder than it should be <br /><br />and in this case i thing the most likely cause is that that the crappy merc controls are not pulling the carb to the idle stop and the barrel on the cable is going to need a turn or two so that it gets pulled to the same spot 100% of the time <br /><br />if you read the whole service manual deal your supposed to set the idle with the cable disconnected and then replace it being sure that its adjusted correctly to get the same idle everytime you move the control<br /><br />its a BIG pain to do right but if you dont skip any steps its works very well and doesent stall right before you hit that other boat at the dock <br /><br /><br />tommays

 

[SteveRay]

Re: 92 Merc 3.0L Idle Question

Thanks for all the replies. I understand what has to be done know and like I said earlier I was just looking for reassurance and a bit of clarification.

 

[trog100]

Re: 92 Merc 3.0L Idle Question

took me a while to get my 3.0 idling nice and slow and reliably and yep the crappy merc controls didnt always return the linkage back fully against the stop..<br /><br />slow and reliable idling is more important to me than most.. my boat is a river boat and a twenty mile trip involves negotiating seven locks and anything up to 150 or so gear changes.. and i really do have to use reverse gear as a brake.. i like it as slow as it will go so as to keep dogclutch wear down.. but if the damn things stalls when i hit reverse its a major problem.. finding the sweet-spot took a while..<br /><br />concrete locks designed (many years ago) for 100 ton steel working barges and plastic boats dont mix that well.. its all too easy to to leave half your boat behind each time u go thru one..<br /><br />trog100

 

[SteveRay]

Re: 92 Merc 3.0L Idle Question

Trog I too boat in the rivre but thank God I do not have to deal with locks as you do. I do dock at a marina once and a while and it is quite embarrasing if you try to reverse brake and then it happens.....the motor dies and you crash into the dock . <br />This all started with me wanting to ensure that my engine was idling at the right rpms to avoid that whole issue but most of all to avoid ecess wear on the outdrive. <br />It does not stall so I guess I will have to wait till the rain stops to put her in the water and see what she idles at.