wont idle at low rpm's

[chapr]

I have a 1999 mercruiser 5.0. The boat starts and runs great, except does not like to keep running at low idle speed. When idling at 6,000 rpm slowly drops down to 4,000 to 3,000 and then dies. If I bump the throttle to about 10,000 we are OK again until we get back to 6,000 then she drops again. Makes it hard to NO-WAKE or to safely dock the boat. any suggestions on where to start? I had the same symptoms after a carb adjustment and a tune-up, I didn't replace the rotor because I could not get it off. tried to pry it off but was afraid of damaging the distributor. any suggestions would be greatly appreciated.......Thanks in advance Chapr

 

[CaptainMak]

Re: wont idle at low rpm's

Bump the throttle to 10,000 rpm ??? Wow. That's insane.

I'd say start looking at your timing or fuel supply. When you did the tune-up, you didn't accidently move the distributor any way, did you ? That would throw off timing a bit.
Also, did you replace all the fuel filters with the tuneup ?

 

[bspeth]

Re: wont idle at low rpm's

Yea if your tach is correct your engine probably blew up unless you pulled it out of Jeff Gordons car. Did you add an extra zero by accident?

 

[Bondo]

Re: wont idle at low rpm's

I have a 1999 mercruiser 5.0. The boat starts and runs great, except does not like to keep running at low idle speed. When idling at 6,000 rpm slowly drops down to 4,000 to 3,000 and then dies. If I bump the throttle to about 10,000 we are OK again until we get back to 6,000 then she drops again. Makes it hard to NO-WAKE or to safely dock the boat. any suggestions on where to start? I had the same symptoms after a carb adjustment and a tune-up, I didn't replace the rotor because I could not get it off. tried to pry it off but was afraid of damaging the distributor. any suggestions would be greatly appreciated.......Thanks in advance Chapr

Ayuh,.... Welcome Aboard,.... Idle should be 650/ 700 rpms in gear, in the water,...

Any lower, 'n it's Gonna die,...

Wot should be 'bout 4800 rpms,...

 

[airshot]

Re: wont idle at low rpm's

You need to get that old rotor off and replace it with a new one. If prying did not work then take a small prick punch or awl for wood and give it a good tap in the center after breaking off the metal firing pin, in fact try pulling up on the metal firing pin on the old rotor.
By stricking it with a punch the plastic will crack and allow the rotor to expand so you can remove it, don't worry about destroying as you will be replacing it with a new one along with the rest of the ignition components (plugs, wires, cap,etc) Also a possibility your carb is gummed up and will need a rebuild. I assume you meant 600 rpm not 6000 or you would have other more serious problems to deal with.
Never cut corners on a boat, it will cost you much more in the long run, I have 60 yrs of boating to show how true that is.

 

[Bondo]

Re: wont idle at low rpm's

You need to get that old rotor off and replace it with a new one. If prying did not work then take a small prick punch or awl for wood and give it a good tap in the center after breaking off the metal firing pin, in fact try pulling up on the metal firing pin on the old rotor.
By stricking it with a punch the plastic will crack and allow the rotor to expand so you can remove it, don't worry about destroying as you will be replacing it with a new one along with the rest of the ignition components (plugs, wires, cap,etc) Also a possibility your carb is gummed up and will need a rebuild. I assume you meant 600 rpm not 6000 or you would have other more serious problems to deal with.
Never cut corners on a boat, it will cost you much more in the long run, I have 60 yrs of boating to show how true that is.

Ayuh,.... For some reason, Merc Glues the rotor on,....

I bust 'em off by grabbin' it with pliers, 'n Twistin'/ snappin' it to pieces,...

'n, No, I don't glue the replacement on,...
It ain't like it can go anywhere,...