Suzuki dt3.5 running problem

steve66

Seaman
Joined
Dec 4, 2007
Messages
50
Hi i have a pair of identical Suzuki dt 3.5 outboards with an identical problem.They both start no problem and run for a few seconds then die.I have stripped and cleaned the carbs,checked the reeds, checked the ignition and checked the fuel to the carb which runs out when the fuel pipe is disconnected.It seems and sounds as if the bowl is running dry as the revs increase before it dies.As well as a gravity fed tank it has a fuel connector to run a remote fuel tank and a fuel pump.I have ruled out the fuel pump being the cause as when the fuel line is detatched from the carb fuel pours out.Has anyone else encountered this problem and a solution will be greatly appreciated.
Regards Steve
 

steve66

Seaman
Joined
Dec 4, 2007
Messages
50
Re: Suzuki dt3.5 running problem

Yes, the vent is open and besides the tank is 3/4 empty.Cheers for your reply
 

steve66

Seaman
Joined
Dec 4, 2007
Messages
50
Re: Suzuki dt3.5 running problem

I found out if i manually choke it with the choke open it runs fine if a little rich.Could someone tell me the oil mixture and if anyone has any info about stripping and cleaning these carbs it would be appreciated.
Steve
 

steve66

Seaman
Joined
Dec 4, 2007
Messages
50
Re: Suzuki dt3.5 running problem

Hi Viv,Thank you for your diagram,although the engines are different the carb looks very similar.How did you get on with cleaning you carb?
 

viv

Cadet
Joined
Nov 30, 2006
Messages
18
Re: Suzuki dt3.5 running problem

I don't really know what I am doing... But it looks a lot cleaner now. There was a lot of sticky stuff all over. It will be a while before I can test it. I need to replace the points because I have no spark yet.

This helped me a lot:
http://www.dansmc.com/carbs.htm
(and here on the forum of-coarse)
 

steve66

Seaman
Joined
Dec 4, 2007
Messages
50
Re: Suzuki dt3.5 running problem

Hi i posted this problem a while back,but still havent been able to source the problem.They start on choke no problem,push the choke in and they run for about 10 seconds then die.Then it takes a few pulls on choke to get started again.I have replaced the reeds,skimmed the head flat,replaces the head gasket,good compression.Fuel pump works fine,stripped the carb and cleaned,float not sticking.
Any ideas please im pulling my hair out!!!
Ps Its a mikuni carb
 

kaferhaus

Petty Officer 1st Class
Joined
Dec 17, 2008
Messages
250
Re: Suzuki dt3.5 running problem

Have you tried keeping it revved as soon as it starts or are you just letting it idle?

If it's only doing it at idle or just off throttle then it's the slow speed jet clogged. If it will still stop when at half throttle or so (high speed circuit partly open) then you still have issues with the main jet passage also.

It's certainly a carb blockage.
 

steve66

Seaman
Joined
Dec 4, 2007
Messages
50
Re: Suzuki dt3.5 running problem

Hi ,Yes it will run over half throttle,thanks for your advice.I have an industrial ultrasonic cleaner,could anyone suggest a good cleaner to add to the water?
Steve
 

kaferhaus

Petty Officer 1st Class
Joined
Dec 17, 2008
Messages
250
Re: Suzuki dt3.5 running problem

Well with the ultrasonic cleaner you need non-flammable carb cleaner. Napa used to carry it in a quart can. I haven't bought any in a long time as it lasts forever...

If your's is like mine and has a heater, there's a product used for removing iron and other stains from bathrooms... think it's called "CLR"... I've used that with good success too.

Just make sure the area is well ventilated.

I assume you have an air compressor? All the passages really need to be blown out also. some carbs have a little rubber or plastic plug that covers the low speed jet... make sure you remove it and the jet if yours has one.

And as an after thought.... you do have the mixture screw adjusted properly???? I can't tell you how many guys have spent days trying to fix a carb "problem" only to find out that the screw is turned all the way in...
 

steve66

Seaman
Joined
Dec 4, 2007
Messages
50
Re: Suzuki dt3.5 running problem

Hi,Yes it has a heater and i do have a compressor and have adjusted the mixture,unfortunately i live in the uk so we dont have napa stores.I have some strong traffic film remover and was wondering if this would work.I will put a search in google for carb cleaner.Thanks again for your help.
Steve
 

steve66

Seaman
Joined
Dec 4, 2007
Messages
50
Re: Suzuki dt3.5 running problem

Hi all I have now stripped the carbs, soaked all the jets in carb cleaner thoroughly cleaned all orrifices and galleries with carb cleaner,put the carbs in a ultrasonic bath at 60 degrees with cleaning solution for 6 hours.Removed dried and cleaned again with carb cleaner and blew out with compressed air to the maximum output my compresser will give me.Reassembled and still exactly the same,dies after a few seconds at anything under half revs.Did a compression test was showing 105 psi,checked points they were spot on.Please has anyone got any more ideas or could tell me where i can view an exploded diagram for the mikuni carb.I really am at my wits end now!!!
Regards Steve
 

cousinabe

Senior Chief Petty Officer
Joined
Nov 13, 2001
Messages
765
Re: Suzuki dt3.5 running problem

here are some parts diagrams which may help... select your appropriate year based on the serial number.

here's what I have interpreted from your posts.
1) starts fine and stalls after 10 seconds.
2) it will run fine at WOT wide open throttle. no stalling.

so, if it's stalling only at idle, it sounds like a low speed jet/air mixture problem.

http://store.brownspoint.com/dt3_5.asp

look at the carburetor figure, part numbers 11, 12. I'm not sure of the specs for the adjustment settings. i would tighten to lightly seated and then back out 1 turn as a start.
 

steve66

Seaman
Joined
Dec 4, 2007
Messages
50
Re: Suzuki dt3.5 running problem

Hi Cousinabe,thank you for your reply and link.I started with the low speed jet screwed in and tried it at different settings but with no difference.Will have another crack at it in a couple of days.
Regards Steve
 

Whoopbass

Chief Petty Officer
Joined
Jun 29, 2006
Messages
638
Re: Suzuki dt3.5 running problem

Sounds like your motors should be running fine with everything you've done.

The only advice I have is to manually push in the valve stem on the fuel needle and blow it out with compressed air or clean it somehow with the valve open. I don't know if it will do anything but you have done everything else.
 

James R

Commander
Joined
Feb 1, 2007
Messages
2,571
Re: Suzuki dt3.5 running problem

Fuel pump old son. You may get enough fuel to run the motor at high RPM but if the fuel pump is not up to par slow running will fail.
You are running a risk with a bad fuel pump. A lean mixture will burn the motor out.
Ex limey.
 

steve66

Seaman
Joined
Dec 4, 2007
Messages
50
Re: Suzuki dt3.5 running problem

Ok here we go!!.Replaced the reeds,fuel pump,plug low speed jet and still the problem is the same.Compression are all above 100psi.As most of you have commented it sounds like the carb,but i have soaked and put in my industrial ultrasonic cleaner for hours then dried off and blew out with compressed air and still the sameThere must be parts of the carb still blocked.Has anyone got an exploded diagram of the carb and/or has had similar experiences?
Steve
 

Whoopbass

Chief Petty Officer
Joined
Jun 29, 2006
Messages
638
Re: Suzuki dt3.5 running problem

Click on the Brownspoint link in the above post if you want an exploded diagram.

Use a thin wire like a bread tie to clean out the orifices. I have had good success with paint thinner to clean my carbs.

It's odd both motors are suffering the same problems and even stranger that they aren't running like new after everything you've done to them. Health wise you might be better off if you just sell the darn things.
 
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