# Merc 6HP 4 Stroke - only runs at speed with the choke out ??



## Brett (Jul 16, 2008)

I think your high speed jet is partially blocked.
By closing the choke you increase the vacuum in the throat
and force a fuel flow into the intake manifold.
I'd do a complete rebuild of the carb.
I've got the Nissan version of the same engine.
Same problem solved by cleaning the entire fuel system
and then doing a complete rebuild of the carb.
The carb kit cost less than 40 dollars. 
Very simple carb to work on, only hard part is the primary bolt closest to the flywheel.
Almost no room to work a wrench.


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## noeettica (Sep 23, 2007)

Post some photos of the motor and carb ...

there should be a main jet in the bottom of the carb and possibly an emulsion tube above that 
get them out and cleaned and you will be well on your way to getting this fixed


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## RustyReel3755 (Jun 1, 2009)

OK, here are some pics, hopefully.  I removed the black screw at the bottom of the carb bowl and flushed it out a couple of times with carb cleaner.  The gas that came out of it when I first opened it looked clean.  

Haven't had a chance to mess with it any more but hope to do so over the weekend.


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## Brett (Jul 16, 2008)

You've got 2 open hose connections on top of the carb.
Are there hoses or caps that cover those 2 barbs?
If not, that may be your problem, an air leak.


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## TomFL (Oct 2, 2007)

> You've got 2 open hose connections on top of the carb.
> Are there hoses or caps that cover those 2 barbs?
> If not, that may be your problem, an air leak.


Brett, if he's got that much air coming in past the butterfly I think it'd idle at 3,000 RPMs 

-T


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## Brett (Jul 16, 2008)

No, I gave that some thought before posting,
Had an old Carter YF that actually idled better with a vacuum line disconnected,
and would stall out when you increased the throttle.
I miss those old engines. Now you can't work on a car
without a serial cable, 200 bucks worth of software and a laptop computer.


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## RustyReel3755 (Jun 1, 2009)

Those open hose connections had me wondering as well.  In case you have not figured it out, I'm not much of a mechanic.

Searched Merc parts sites for pics of the carb.  They all had the same drawing with not much detail, those ports were not shown.

Did an Ebay search and found two listing for the same year and size motor with pictured detailed enough to see the carb.  Both of those motors also had these ports uncovered.  So I'm guessing that is the factory set-up?

They must do something, however, as this AM when I had the motor at idle I covered them with my fingers and the motor started to sputter.

I don't know.  Still gonna give the seafoam a try when I can get around to it.  Some guys claim it works wonders....others not so much.

Thanks guys.


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## noeettica (Sep 23, 2007)

Had to jump through some hoops to post this but here U go ...










Dave


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## Brett (Jul 16, 2008)

that's one way to get a screenshot Dave... ;D

Here's a piece of software that lets you capture an image direct from your desktop...

http://download.cnet.com/Gadwin-PrintScreen/3000-2094_4-10123018.html


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## noeettica (Sep 23, 2007)

Thanks I will try that ... I took a photo of the desktop screen... Loaded it into the notebook then put it on photobucket then refreshed photobucket on this machine and pasted the Link
  

Oh Btw Cheap OLD Nikon 775 These early point and shoots work great ! 775 , 880 , 885 & 5000 Got a bunch of 'Em LOL


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## RustyReel3755 (Jun 1, 2009)

Thanks NoeTtica, that is the one I found. Doesn't show the vacuum ports on the top of the carb and what, if anything, gets attached to them. Tks, and sorry for the jumpin' thru the hoop.


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## RustyReel3755 (Jun 1, 2009)

Thanks guys.  Sea Foam did the trick.  Roarin' to go now!!  Actually, I'm still puttering along since it is only a 6 horse, but better than before.


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## TomFL (Oct 2, 2007)

> Thanks guys.  Sea Foam did the trick.  Roarin' to go now!!  Actually, I'm still puttering along since it is only a 6 horse, but better than before.


Awesome!

-T


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