Idle Adjustment? Suzuki 6HP, 2012, need some quick help

CloudDiver

CloudDiver

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Sep 8, 2014
2,551
Catalina 22 Swing Keel San Diego
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My Dinghy outboard is cutting out at low idle. 2012 Suzuki DT6 standard shaft, bought from PO with the Achilles 10ft air-floor inflatable.

He had a new carb and impeller installed just before selling it to me, probably because he never ever did maintenance on anything considering the overall condition of his big boat...

Anyway, the idle screw at the top is all the way 'in', and (after fully warming up) the motor still dies out and will only stay running at a fast idle or what I would consider about 1/3 throttle. Is this a throttle cable adjustment? Deeper dive into low idle mixture screw?

I can't seem to find a video or on-line guide for Tohatsu/Merc/Suzuki 5 or 6 hp with this carb... Don't have the maintenance manual either.

Any help? Here is a pic of the carb;
 
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Leeward Rail

Leeward Rail

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Mar 20, 2015
3,095
C&C 30 Mk1 Winnipeg
Only thing I can find is a manual for suzuki outboards up to 2003, would that work ?
 
M

markwbird

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Nov 26, 2012
1,653
Hunter 34 Berkeley
I had that same engine. That was just before ethanol became widespread in gasoline. The fact that he replaced the carb tells me he was probably having the same problems I was. Specifically, gunked up carb due to ethanol in the gasoline. The ethanol caused two problems; It dissolved the rubber fuel lines and sent the gunk from that into the carb and it rusted some of the stainless steel components in the carb. (ethanol attracts moisture from the air). I was able to greatly reduce the problem by installing a filter on the fuel line from my remote tank and replacing all of the fuel line within the engine housing with ethanol rated line from West Marine. AND. I always ran the carb dry at the end of the day. Not sure if your problem is ethanol related but it could be.
 
CloudDiver

CloudDiver

.
Sep 8, 2014
2,551
Catalina 22 Swing Keel San Diego
markwbird said:
I had that same engine. That was just before ethanol became widespread in gasoline. The fact that he replaced the carb tells me he was probably having the same problems I was. Specifically, gunked up carb due to ethanol in the gasoline. The ethanol caused two problems; It dissolved the rubber fuel lines and sent the gunk from that into the carb and it rusted some of the stainless steel components in the carb. (ethanol attracts moisture from the air). I was able to greatly reduce the problem by installing a filter on the fuel line from my remote tank and replacing all of the fuel line within the engine housing with ethanol rated line from West Marine. AND. I always ran the carb dry at the end of the day. Not sure if your problem is ethanol related but it could be.
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Good to know... but as of now the carb is brand new. It will run fine at 1/3 throttle and the pisser is shooting strong, it will just cut out as soon as you try to go to low idle. I just need to figure out this idle adjustment and I should be good for the 4th. I'll keep the filter in mind, and I usually run Seafoam in my fuel even if I'm not storing it for long.
 
CloudDiver

CloudDiver

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Sep 8, 2014
2,551
Catalina 22 Swing Keel San Diego
Well, first mistake is when asking for help, get the year right for the motor. Doh! My DF6 is a 2012 (verified by serial number). I was wondering why the diagrams in the manual look nothing like my carb... Anyway, now we are getting somewhere. Thanks for the links fellas!
 
capta

capta

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Jun 4, 2009
4,772
Pearson 530 Admiralty Bay, Bequia SVG
I had a similar problem with our Johnson and after a new carb and a bunch of other work, we found out it was the fuel pump. Considering someone screwed in the idle screw all the way, I'm guessing the tech who installed the carb found that a new carb didn't solve the problem.
 
CloudDiver

CloudDiver

.
Sep 8, 2014
2,551
Catalina 22 Swing Keel San Diego
capta said:
I had a similar problem with our Johnson and after a new carb and a bunch of other work, we found out it was the fuel pump. Considering someone screwed in the idle screw all the way, I'm guessing the tech who installed the carb found that a new carb didn't solve the problem.
Click to expand
The pic I posted above my is not my actual carb, its a stock pic.... PhotoBucket now wants money for third party hosting so I have to find a new pic strategy. Anyway, the above pic is identical to my motor, but judging from the loos of everything inside my cowl I think my fuel pump is new also. Very valid point @capta but I believe the the P.O. paid for the new parts so he could sell the motor but did not pay for the tune up.
 
CloudDiver

CloudDiver

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Sep 8, 2014
2,551
Catalina 22 Swing Keel San Diego
Last night I pulled the four screws on the top cover plate and took a look inside, that is where all the jet adjustment screws are. What confuses me is the gasket on that cover. I have a feeling that if the cover is off you loose vac on the carb, so how can you adjust the jets while running? Maybe that cover just keeps water out? I dunno... removing that cover is a royal pain, the idle screw has to be removed and the throttle cables loosened so everything comes out of the way to get the plate to slide out. Anyway you slice it it seems you can't do any any adjustments to the fuel-air mix at idle while running the motor!
 
Brian D

Brian D

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Feb 17, 2006
5,274
Lancer 27PS MCB Camp Pendleton KF6BL
@CloudDiver, you may be thinking this way too hard. Start by adjusting the throttle lever. The idle may just be too low. Do you have a digital tachometer that you can use to check the idle RPMs? That is where I would start. But just so you know, on both of my outboards (Yamama 9.9 and Suzuki 2.5) the jets needed cleaning. She would run at high RPM but at low RPM the motor was starved for fuel due to the clogged jets.
 
CloudDiver

CloudDiver

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Sep 8, 2014
2,551
Catalina 22 Swing Keel San Diego
Brian D said:
@CloudDiver, you may be thinking this way too hard. Start by adjusting the throttle lever. The idle may just be too low. Do you have a digital tachometer that you can use to check the idle RPMs? That is where I would start. But just so you know, on both of my outboards (Yamama 9.9 and Suzuki 2.5) the jets needed cleaning. She would run at high RPM but at low RPM the motor was starved for fuel due to the clogged jets.
Click to expand
Thanks Brian... I pretty much have little choice at the moment but to go by trial and error. I'm hoping there is no issue with the jets since the carb is new. Adjusting the throttle cables manually seems like the best place to start.
 
CloudDiver

CloudDiver

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Sep 8, 2014
2,551
Catalina 22 Swing Keel San Diego
Well, I just ran the the motor in the test tank again (55 gal trash can). The idle screw is essentially useless at this point, no amount of adjustment changes the situation.
Good news is I am pretty sure exactly what the problem is, the idle mix jet or slow air jet is not set right (part 18 on the link below). Could also be the pilot jet (part 15) since it does not look like the slow air jet can be turned without taking the whole carb off. Anyway, I'm fairly sure of this because the motor runs perfect with the choke on at low idle. As soon as you push the choke back in you have to carefully set the throttle so it does not sputter out. Seems there is not issue shifting into gear while choke is in or out. So at least on the 4th of July I can run the motor, I just have to be mindful of pulling the choke out each time I want to idle, otherwise it'll just cut out and I'll have to pull start again. At least I can get by for now.

Carb Diagram;
http://www.brownspoint.com/store/pc/bp_AP_AssemblyDetail.asp?ID=3158
 
Gunni

Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
I don't see ANY adjustable jets on that carburetor... Pretty much SOP on modern small engine carbs. What you have is a series of preset jets in circuits. Poor slow idle is symptomatic of a clogged jet, nozzle or passage, very possibly by difficult to remove hard deposits.
 
CloudDiver

CloudDiver

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Sep 8, 2014
2,551
Catalina 22 Swing Keel San Diego
In summary, after running the motor on the water for about 3 total hours on 3 and 4 July, I pretty much don't have any major issues while actually operating. As long as the choke is pulled it will idle at the speed your ear expects to hear a slow idle. As soon as you push the choke in it idles at what sounds like 1/3 throttle. As far as running in Fwd, no issues at all except that I think my slowest speed is just a bit too fast but as far as RPMs go it is running pretty quiet. I guess the only thing to be mindful of is that because of the fast idle in neutral there is a bit of a jarring surge fwd when shifting from N to Fwd. Its not bad when you are prepared for it and not nearly as bad with two people plus gear in the boat than it is just solo.
 
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