carb idle fuel questions(1980 50hp 4cyl mariner)

[plazmore]

hey...

I rebuilt my carbs, and after had no idle...runs fine at speed...

if I lift the lever enough to keep it idling, and turn the idle mixture screw closed on the bottom carb, the engine dies...

if I do the same on the top carb, no change occurs...

I assume this means the upper carb is supplying no fuel at idle...

I have looked at this several times now, and am stumped...

I can see thru the hole when disassembled, so I know its clear....

what else controls idle fuel?

or in other words, help!

any input is as always, welcome...thanks.

 

[achris]

Re: carb idle fuel questions(1980 50hp 4cyl mariner)

It might be 'supplying no fuel' if the cylinder is not sucking any in. With the engine running put your hand up next to the carb and 'feel' for sucking. Do it on both carbs so you know what it should feel like.

Chris......

 

[plazmore]

Re: carb idle fuel questions(1980 50hp 4cyl mariner)

suction in both is strong...also, as I move the lever for idle speed up, the rpms jump to high speed, like a light switch. no in between...has full power on the water...I took off the carb again, cleaned all passages again. am thinking there is one I cant see that's blocked...cant imagine what else it could be...I can see thru all the others...

 

[achris]

Re: carb idle fuel questions(1980 50hp 4cyl mariner)

Sounds like an idle circuit problem... Some of those carbs have a welsh plug on the top (it's the supply reservoir for the idle circuit), and dirt can accumulate in that area. I'm not sure if the carb overhaul kit contains a new plug. If it does, just pop the old one out and clean all the internal passages with carb cleaner and dry compressed air. If you can't remove the plug try disassembling the carb as much as possible, then soaking it in carb cleaner for a few days.

Chris....

 

[plazmore]

Re: carb idle fuel questions(1980 50hp 4cyl mariner)

thanks for the input...I have it off again right now...soaking in carb cleaner...I see the path the idle fuel takes...will clean thru...
the kit did come with plugs...any tips for popping and reinstalling? I am getting pretty good at this...off, redone, back on in an hour or so...

amazing how well this old motor runs, except for this idle thing...cant wait to get out on the sound...

couldn't take it out for seafair, since it wont idle...but I have run at wot and she purred and went full speed in no time...pushing a heavy tri hull...

thanks again!