Weird idle senario, looking for ideas

[JasonF]

I inherited a boat motor combo and have been restoring both but have run into hopefully a minor glitch with the motor.
The motor is a 74 50hp Evinrude that I have personally never ran on the water (typical of most questions )
The motor ran from the start but never has idled all that great. I've soaked the carbs twice and put a rebuild kit in along with all new fuel lines. Fuel pump is good and compression is excellent.
Since the work I've done so far, the motor runs pretty smooth and idles nicely with the warm up lever about half way up. The problem comes when I try to idle it all the way down, basically the motor just stalls out. I have tried adjusting the low speed idle endlessly to no avail. The manual states a 5/8 turn out and I've read 1.5 turns out on the forums here for the low idle so I've tried both along with everything inbetween.
I also notice that when I try to rev the motor by manually turning the throttle lever on the carbs that there is a slight hesitation until the motor revs up, don't know if this is related or not.

I'm sure the motor will run in this condition as I can quickly shift into drive and manage to keep the motor running, its just that I know its not quite right.

Thanks in advance
Jason

 

[jonesg]

Re: Weird idle senario, looking for ideas

You might be trying to set it too low.

They idle quite high on a hose, around 1100rpm.
That will drop down to 700 in the water.
Its supposed to be final set in the water.

 

[JasonF]

Re: Weird idle senario, looking for ideas

You might be trying to set it too low.

They idle quite high on a hose, around 1100rpm.
That will drop down to 700 in the water.
Its supposed to be final set in the water.

Thanks for the reply.
Actually I've been doing my testing in a tank, the idle sounds about right when the warm up lever is half way up. Just can't get the same results without the warmup lever.

 

[G DANE]

Re: Weird idle senario, looking for ideas

Do you have a manual ? Be aware that the correct adustment of the iddle speed is at a screw at the linckage, not the iddle mixture screws. Raise iddle speed till its smooth running, at the iddle speed screw. Then reduce till it starts to be unstable, then correct mixture at iddle misture screws, a tiny bit at a time, waiting for motor to respond, then lower iddle speed a bit and repeat procedure, till you are where you want to be. When you try to rev up by pulling in carb linckage, it will hisitate, since ignition timing isnt advanced. When you rev up by raising warm up lever, you advance ignition timing at the same time, thats the reason you shouldnt attempt to adjust anythin as long as it is running at warm up lever. Be aware that the syncronisation between ignition advance and carb butterfly opening is essential for a smooth running motor, That should be set first. Maybe your library has manuals, some do.

 

[JasonF]

Re: Weird idle senario, looking for ideas

Do you have a manual ? Be aware that the correct adustment of the iddle speed is at a screw at the linckage, not the iddle mixture screws. Raise iddle speed till its smooth running, at the iddle speed screw. Then reduce till it starts to be unstable, then correct mixture at iddle misture screws, a tiny bit at a time, waiting for motor to respond, then lower iddle speed a bit and repeat procedure, till you are where you want to be. When you try to rev up by pulling in carb linckage, it will hisitate, since ignition timing isnt advanced. When you rev up by raising warm up lever, you advance ignition timing at the same time, thats the reason you shouldnt attempt to adjust anythin as long as it is running at warm up lever. Be aware that the syncronisation between ignition advance and carb butterfly opening is essential for a smooth running motor, That should be set first. Maybe your library has manuals, some do.

Thank You, you just gave me some good direction.
I do have a manual and it says everything that you said except for the part that the idle speed is at a screw in the linkage. The way I was reading it was that I was so use the idle mix screws.

Thanks again, I will post results.