Suzuki DF2.5 won't idle...

Iain C

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My outboard has always been very reliable, however suddenly it won't idle, and will often stall when brought up from low revs. This happened suddenly. Started and ran fine on my mooring, problems by the time I got to the pontoon. Ran it up in the garden last night and no better.

I cant see anything obvious, I've cleaned the plug, although I did see a tiny bit of white corrosion residue around a bit of the head gasket. Could this be head gasket failure? Blocked carb jets?

It starts fine and seems OK at full chat, it's just the idling is an issue. Any advice welcome.

Thanks!
 

VicS

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Always worth trying a new plug.

But sounds as though the carb needs a clean

You dont say what age or give the serial number but it should look something like this

fig005.jpg
...... parts list at http://www.brownspoint.com/store/pc/BP_AP_AssemblyDetail.asp?ID=7

clean the main emulsion tube (#2) and the jet (#3) but most likely the slow running passages in the carb body require attention esp the air jet #17, the pilot air jet #18 and the pilot jet #15.

Dont know what AngusMcDoon means by the "idle jet needle" perhaps he can identify on the above diagram.


when dismantling/ cleaning/ rebuilding watch out for the little clip #7 linking the float arm and the needle valve #4.
 
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Iain C

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Cheers guys. I took the carb off and there was a teeny bit of oil around it, I gave it a quick wipe but I guess I'll need proper carb cleaner and a strip if the jets are gummed up. I'll order a service kit at the same time with a plug etc and take it from there.
 

macd

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Carb cleaner is the method purveyors of snake oil prefer.
Strip the carb: it's really simple, especially since almost anyone can video or photograph the process these days. Clean out air/fuel passages and jets with an air-line. Best not to poke jets with anything hard.
As VicS advises, take special care with that clip/float assembly. It's often possible to assemble them the wrong way.
 

AngusMcDoon

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Dont know what AngusMcDoon means by the "idle jet needle" perhaps he can identify on the above diagram.

Just sloppy terminology. I would expect it's no. 15 that is gummed up. Being a nerd I don't like calling what should be called a nozzle a jet as a jet is (being pedantic) actually the resulting stream of fluid and not the component that creates it. However, I realize that everyone calls them jets.
 
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steve66

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Angus is quite correct, i have repaired a number of these carbs. If you can remove pilot jet #15 excellent but i have had cases of the being completely seized. There is also a welch plug hiding the slow running jet. This plug needs to be removed and jet adjusted.
Just sloppy terminology. I would expect it's no. 15 that is gummed up. Being a nerd I don't like calling what should be called a nozzle a jet as a jet is (being pedantic) actually the resulting stream of fluid and not the component that creates it. However, I realize that everyone calls them jets.
 

Iain C

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Holy thread resurrection Batman!

I've done very little sailing over the past few years (building houses, having kids...) but back on it now. This outboard got progressively less reliable until I stopped using it completely. Anyway, to cut a long story short, the plug was getting wet...water wet that is! Stripped it down and the head gasket looked very suspect.

One very simple question...what is the correct torque setting for the head bolts for this outboard? Can't really find anything online...
 

VicS

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Holy thread resurrection Batman!

I've done very little sailing over the past few years (building houses, having kids...) but back on it now. This outboard got progressively less reliable until I stopped using it completely. Anyway, to cut a long story short, the plug was getting wet...water wet that is! Stripped it down and the head gasket looked very suspect.

One very simple question...what is the correct torque setting for the head bolts for this outboard? Can't really find anything online...

They should be in the manual at http://162.144.28.33/lib/suzuki/manuals/suzuki_1996-2007.html#/0 ................. somewhere!

If not then on page 1-28 there are tables of typical bolt torques vs bolt size
 

Heckler

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Always worth trying a new plug.

But sounds as though the carb needs a clean

You dont say what age or give the serial number but it should look something like this

fig005.jpg
...... parts list at http://www.brownspoint.com/store/pc/BP_AP_AssemblyDetail.asp?ID=7

clean the main emulsion tube (#2) and the jet (#3) but most likely the slow running passages in the carb body require attention esp the air jet #17, the pilot air jet #18 and the pilot jet #15.

Dont know what AngusMcDoon means by the "idle jet needle" perhaps he can identify on the above diagram.


when dismantling/ cleaning/ rebuilding watch out for the little clip #7 linking the float arm and the needle valve #4.

Nail on head as usual, a common fault on these. They leaned them right down to pass emission tests and the slightest bit of obstruction and they do stupid. I am of the old school, poke with a bit of wire for the best job. carb cleaner = snake oil in cases like this. I recall a similar thread a while back and someone actually drilled the jet out to make it a perfect job. California wouldnt be happy but hey ho!
PS just realised, Duh!
 
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Chris_Robb

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And to perpetuate this old thread - but still obviously informing people.

The Cause of the blockage: I was told by a Greek engineer back in 2012, when the jet blocked after only a few weeks - several times, that the cause is our habit from two stroke days of always running out the fuel from the carb every time you stopped it (at the end of the day) Each time you dry out the jet a little gum remains, and this builds up and blocks very quickly.

I thought is was probably bull shit, but I followed his advise a never run the fuel dry, but when I take the outboard off to store, I drain the Carb bowl via the appropriate screw - designed for that very purpose.

Its now 2018 and I have never had a repeat of the problem. Who runs their lawn mower dry? there isn't any way to do it. so its just not necessary - unless you have a seagull on 25% oil or what ever they ran on!

Good little engine - no regrets in buying - so light and easy to deal with - now never lets me down.
 

Bob the Dog

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Have one of these and they a great outboards bar the carb. If your unit is over 4 years old the carb has airways that are only a couple of thou's wide. With the rubbish petrol available nowadays that is dosed with bio, which absorbs water very quickly, the metal used efflorescences and both air ways and jets corrode before your very eyes. I have two spares that are wrecked if you want to practice taking them apart!! If you are finding the carb drain stiff/seized then the whole unit is on its way out. A new model is slightly redesigned and isn't as quick to die. At the risk of causing a fight on the forum consider removing any pump petrol if you don't use it within the week and sticking a cup full of Aspen in it and then run it to flush the innards of standard water soaked petrol. As far as stuff on the web re changing jets, if only we could. The articles are quite old and refer to very outdated carbs. Even 6 year old models don't have adjustable jets under the caps that the articles tell you to drill out. I have washed/ultrasonically cleaned two of these carbs and yes, this will usually shift the crud but not the corrosion caused by the moist petrol. I bought a new style model and leave it with Aspen in it if being left idol. It's stored on the stern rail with just a cover and starts first pull every time. £5 for a years worth against £100 for a new carb. Progress.
 

Heckler

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Have one of these and they a great outboards bar the carb. If your unit is over 4 years old the carb has airways that are only a couple of thou's wide. With the rubbish petrol available nowadays that is dosed with bio, which absorbs water very quickly, the metal used efflorescences and both air ways and jets corrode before your very eyes. I have two spares that are wrecked if you want to practice taking them apart!! If you are finding the carb drain stiff/seized then the whole unit is on its way out. A new model is slightly redesigned and isn't as quick to die. At the risk of causing a fight on the forum consider removing any pump petrol if you don't use it within the week and sticking a cup full of Aspen in it and then run it to flush the innards of standard water soaked petrol. As far as stuff on the web re changing jets, if only we could. The articles are quite old and refer to very outdated carbs. Even 6 year old models don't have adjustable jets under the caps that the articles tell you to drill out. I have washed/ultrasonically cleaned two of these carbs and yes, this will usually shift the crud but not the corrosion caused by the moist petrol. I bought a new style model and leave it with Aspen in it if being left idol. It's stored on the stern rail with just a cover and starts first pull every time. £5 for a years worth against £100 for a new carb. Progress.
The drilling out refers to the jets themselves, not the blanking bits. the corrosion you refer to I agree and I always deal with it with a wire pulled out of a wire brush.
 

Iain C

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And to perpetuate this old thread - but still obviously informing people.

The Cause of the blockage: I was told by a Greek engineer back in 2012, when the jet blocked after only a few weeks - several times, that the cause is our habit from two stroke days of always running out the fuel from the carb every time you stopped it (at the end of the day) Each time you dry out the jet a little gum remains, and this builds up and blocks very quickly.

I thought is was probably bull shit, but I followed his advise a never run the fuel dry, but when I take the outboard off to store, I drain the Carb bowl via the appropriate screw - designed for that very purpose.

Its now 2018 and I have never had a repeat of the problem. Who runs their lawn mower dry? there isn't any way to do it. so its just not necessary - unless you have a seagull on 25% oil or what ever they ran on!

Good little engine - no regrets in buying - so light and easy to deal with - now never lets me down.

Think you've got the wrong thread fella. My rough running wasn't a gummed up carb...it is head gasket failure and water getting onto the spark plug!
 

Rocksteadee

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Always worth trying a new plug.

But sounds as though the carb needs a clean

You dont say what age or give the serial number but it should look something like this

fig005.jpg
...... parts list at http://www.brownspoint.com/store/pc/BP_AP_AssemblyDetail.asp?ID=7

clean the main emulsion tube (#2) and the jet (#3) but most likely the slow running passages in the carb body require attention esp the air jet #17, the pilot air jet #18 and the pilot jet #15.

Dont know what AngusMcDoon means by the "idle jet needle" perhaps he can identify on the above diagram.


when dismantling/ cleaning/ rebuilding watch out for the little clip #7 linking the float arm and the needle valve #4.

The idle needle is on the far side of the carb, just above the hole for the main fixing bolt.
It is under an alloy cap and is not supposed to be tampered with for the emissions
However the setting is set too lean to ensure it meets those emissions
Drill it out
 
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