Rough idle/starting

[XtcVisions]

I have a 1997 crownline 176 Br with a mercruiser 3.0lx/alpha one drive.

I am going to be doing a tune up tomorrow, replacing fuel filter, water separator filter, oil filter, spark plugs and wires, possibly cap n rotor/distributor, it will start up after i pump it 3 times, then die, then ill pump 3 times again and it will stay running but idle around 1000 rpm on water and idle pretty rough for a little while, after a few WOT runs it will idle with no problem at around 1000 rpm, which i know is high... I am going to post the picture of the serial numbers and such and seeking info to make sure I buy the right parts, we have napa/autozone/academy sports local, and a marine shop that doesnt keep much on hand.

Here is a imgur link to the photo, wouldnt let me upload here.

http://imgur.com/MJQDtDe

 

[XtcVisions]

Also, i know that it is probably the carb that needs cleaned/adjusted, I just bought it recently, so I am wanting to do the tuneup anyways.

 

[alldodge]

If its idleing on its own at 1000, look at the linkage, something is binding or not adjusted correctly

 

[havoc_squad]

After you finish carb rebuild:

If you can push the throttle cable to reduce idle speed after increasing throttle at control box and bringing it back to minimum, your throttle cable preload at the carb is not enough/too much slack.

If you change it, make SMALL adjustments. It usually doesn't take much if it is close.

Once you can get the idle stable after carb rebuild to 750 rpm on muffs fully warmed up following OEM service manual, the next step is final adjustment on the lake fully warmed up, minimum idle rpm in gear, and boat moving.

The factory service manual is spot on for the correct way in doing this.

 

[XtcVisions]

Starting tune up now, spark plugs were pretty much toast

 

[Bondo]

If you can push the throttle cable to reduce idle speed after increasing throttle at control box and bringing it back to minimum, your throttle cable preload at the carb is not enough/too much slack.

Ayuh,...... Welcome Aboard,..... 'bout yer hi-idle,..^^^^ This is important, the cable has to slightly push the throttle linkage against the idle adjustment screw,......

No return springs on boat carbs,...

 

[XtcVisions]

New spark plugs, wires looked good so I didn't change them, new oil filter, new fuel filter, cleaned out the mesh screen where fuel goes into carb, it was pretty gunked up, new oil top and bottom. Seems to run alot better and start up much easier with little to no pumps to get it going. Still idles high, although im not sure how accurate my tach is, it says it is idling around 1500-2k but i know for a fact it is no where near that, maybe 1k at most

 

[alldodge]

See if you can rent/borrow one from a auto parts house to verify

 

[XtcVisions]

Im not 100% sure how to adjust the linkage and such without some photos or something showing me how, or what to look for, i can do routine maintenance but past that I am learning as I go.

 

[alldodge]

Your serial number is 0K018299 and you should have a Merc 2bbl

The idle adjusting screw is on the throttle lever (item 32) and the adjustment is done by using a screw driver and turning the adjustment screw (item 26) which has a spring (item 27) around it.

https://www.mercruiserparts.com/bam/subassembly/30910/2330/70

There is a throttle cable attached to the throttle lever. Remove the cable when setting the idle using a tachometer. Once adjustment is made, adjust cable so it just connects to the carb lever. Then slide back off and rotate the brass barrel one more turn so it helps push the carb closed

 

[havoc_squad]

Just to clarify my wordy babbling, when you finish the steps allDodge said for throttle cable adjustment, there is a quick way to verify it is set right.

First idle speed must be set correctly with accurate tach before you can remove/fix throttle cable slack.

While engine running at idle, move the throttle forward a bit to fast idle speed at the control box and return it back to minimum, then go to the carb and attached throttle cable and gently push it to the minimum.

If the idle stays the same and the idle rpm is in spec, the throttle cable adjustment is done.

 

[XtcVisions]

I will try to get the boat out this week either tues, weds, or thurs thu try to make adjustments then!