1986 Suzuki DT115 Power problem

Numlaar

Chief Petty Officer
Joined
Jul 9, 2009
Messages
633
Hey all,

Well I just bought a new (used) boat, with a 1986 Suzuki DT115 (115HP) with Oil injection...

Compression tested it, and then sea trialed it and it ran great... for about an hour...

On the way back in, it just started dying down (loosing power), and came off plane... Tried to give it throttle and nothing...

Brought it down to idle and it would idle fine... give it full throttle same thing.

While at idle, I could hear a random clicking noise coming from under the cowl... but since I was the only one on the boat, I couldnt go back to see what it was...

It was acting like it lost a cylinder... (Coil?). I know nothing about these motors... always been an evinrude guy...

I brought it back and started it on the muffs, and again it would idle, but about every 30 seconds it would cough really badly, then idle smooth again...

idle idle idle idle, BLEH, idle idle idle, idle, BLEH, idle idle and so on... (best way I can describe it sorry)

Any suggestions on where to start?
 

Numlaar

Chief Petty Officer
Joined
Jul 9, 2009
Messages
633
Re: 1986 Suzuki DT115 Power problem

Oye...

No suggestions eh?

I really hate to take it to suzuki, but I guess I might have to..
 

bowhuntrrl

Petty Officer 1st Class
Joined
Mar 26, 2003
Messages
320
Re: 1986 Suzuki DT115 Power problem

Sounds like carb overhaul time, particularly if the boat has been sitting. The carbs on these Suzukis are touchy, to say the least. E-10 gas is also wreaking havoc with outboards and all marine engines nowadays. I suggest getting your carbs overhauled then adjusted. Use fresh , new gas, and also either Startron or Marine formula Stabil at the least with your gasoline. You will not be able to clean the carbs by spraying carb cleaner in them, they will need to come apart and all the passages blown out.
 

Numlaar

Chief Petty Officer
Joined
Jul 9, 2009
Messages
633
Re: 1986 Suzuki DT115 Power problem

Thanks...

I'll look into it, but it seemed too "all of a sudden" to be carbs...

Also there was the clicking noise I heard... someone told me that these motors have a sensor for the oil injection that limits the power when the oil is low... so not sure if thats it... (oil was near full though).
 

Numlaar

Chief Petty Officer
Joined
Jul 9, 2009
Messages
633
Re: 1986 Suzuki DT115 Power problem

Well in case anyone has or had a similiar issue... it was in fact the carbs...

The main venturi tube on the #1 carb came out completely, so wasnt feeding the high speed jets for that cylinder, so was basically running on 3 out of the 4...

The carbs were SUPER DUPER corroded, had to soak them for a week!

Got them all cleaned, tube reinstalled, and she's back to screaming!

Previous owner did not use a water seperator, or any ethanol treatment of any type! I have since added both, so should be good now for a bit.
 
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