'99 merc 150 xr6 idling too fast

[jbjennings]

Guys,
My friend just bought a '99 150 XR6 and I just ran it (it's at my house) and it is idling way too high--about 1300 RPM's. What can I do to fix this problem. It ran fine and was extremely fast (too fast for me), but since it idled so fast it didn't shift smoothly. Is it carb cleaning time? Can I just clean the idle jets or is it major carb overhaul time? I've never fooled with one of these big 'ol monsters.. Is there an idle adjustment on the motor or controls?
Thanks,
JBJ

 

[trussmonkey]

Re: '99 merc 150 xr6 idling too fast

put it in the water
I've got an 82 115 hp that idles about the same on muffs, but drops to about 850 to 900 rpm when i put it in at the boat ramp.
I don't know why, maybe the extra pressure on the exhaust or that it has to pump water instead of it being forced in.

 

[jbjennings]

Re: '99 merc 150 xr6 idling too fast

I'm seeing 1300 rpm's with it in the water at the lake.....
Thanks though,
JBJ

 

[Don S]

Re: '99 merc 150 xr6 idling too fast

First thing is disconnect the throttle cable (the one from the helm control to the motor) and see if it idle down.
If not, I would highly recommend a complete sync & link. Hard to tell what is messed up.
An OEM service manual would be the first tool he should get for his tool box. It will explain in detail how the process is done.

 

[jbjennings]

Re: '99 merc 150 xr6 idling too fast

Thanks DON,
I'll try that as soon as I get a chance.
JBJ