Motor Stalling

mudcatwilly

Seaman Apprentice
Joined
Aug 11, 2006
Messages
32
I have a 1990 Suzuki DT85 and this has been a long standing issue in the two years that I have owned the boat. It takes at least a dozen times to start and idle when cold starting. When it does start, it then idles for about 20-30 seconds, then dies. It runs fine when the boat is moving, but even with the motor warmed up, it dies when I slow down to idle. It always stalls when I shift from neutral to forward or reverse unless I really slam it into gear.

I have the three carb adjustment screws uniformly turned about 1 3/4 turns out. I ran two full cans of Seafoam through about 6 or 8 gallons of fuel and there has been no improvement. The fuel line and fuel filter is new. I have brand new 4 AWG battery cables (not that it matters). I have not attempted to adjust the idle because I have not learned how to do that yet. For what it's worth, the boat has no tach, but the idle seems low to me. I am no mechanic, but I am willing to starting taking stuff apart if need be. Please help.
 

mudcatwilly

Seaman Apprentice
Joined
Aug 11, 2006
Messages
32
Re: Motor Stalling

If I could get one reply that might give me a starting point, that would help. Thanks
 

bowhuntrrl

Petty Officer 1st Class
Joined
Mar 26, 2003
Messages
320
Re: Motor Stalling

Willy, I'm afraid that you are going to need more than Seafoam !!! You will need to take the carbs off and do a proper rebuild. Only take one apart at a time so you will have a reference should you need it in the other 2.Make sure to put them back in the proper location(top, middle, bottom). I also advise that you get a service manual for reference. What are your compression readings ??? I have an '86 DT85 that I got on a boat last year, it had been sitting 5 years. It might also be a good idea for you to rebuild the fuel pump. Do you pump the bulb up hard when starting?? Do you push the key in to choke?? What is your idle RPM when warm?? This is important to prevent stalling. Sounds like your rpm is too low at idle.I had to install a tach on mine to find the right prop pitch and also set the idle. Tachs are not that expensive and there is connector in the dash harness for one.
 

mudcatwilly

Seaman Apprentice
Joined
Aug 11, 2006
Messages
32
Re: Motor Stalling

Before I attempt to rebuild the carbs, etc., I did want to try and adjust the idle. Can you briefly explain where the idle adjustment is on the DT motor?
 

airframer

Petty Officer 2nd Class
Joined
Nov 10, 2007
Messages
158
Re: Motor Stalling

follow the trigger linkage arm to the tower and you'll see a screw that'll advance the ignition timing. but should definately rebuild your carbs properly like they suggested.
 

mudcatwilly

Seaman Apprentice
Joined
Aug 11, 2006
Messages
32
Re: Motor Stalling

I believe the idle adjust screw is toward the upper left of the photo. Is that right?

 

mudcatwilly

Seaman Apprentice
Joined
Aug 11, 2006
Messages
32
Re: Motor Stalling

It started on the first crank, which is rare (maybe the seafoam from last week helped?). I increased the idle slightly. It seems to want to stall a little less, but it continues to misfire when idling on regular intervals about every 3 seconds. It sounds like: wah,wah,wah,wah,cough...wah,wah,wah,wah, cough..and so on.
 

Yamajoe

Petty Officer 1st Class
Joined
Oct 31, 2007
Messages
264
Re: Motor Stalling

What you are describing sounds like it maybe running just bit lean; turn your air/fuel mixture screws in so they are about 1 1/2 turns out or until the cough goes.
 

mudcatwilly

Seaman Apprentice
Joined
Aug 11, 2006
Messages
32
Re: Motor Stalling

So, if the screws are turned back in, you get more fuel-to-air and if they are turned out, you get less fuel to air? At least that's how I understand it.
 

bowhuntrrl

Petty Officer 1st Class
Joined
Mar 26, 2003
Messages
320
Re: Motor Stalling

So, if the screws are turned back in, you get more fuel-to-air and if they are turned out, you get less fuel to air? At least that's how I understand it.

I could be mistaken, but I seem to remember that these screws actually work opposite to that. I think that the more you open them that the more fuel they allow in. At any rate, you can try it + 1/4 turn both ways to see if it makes any difference as to which way it prefers since that's all that counts ultimately.
 

mudcatwilly

Seaman Apprentice
Joined
Aug 11, 2006
Messages
32
Re: Motor Stalling

It turns out that my problem was due to a slightly malfunctioning choke, but more importantly, low compression in cylinder number 1.

What are my options here? I can replace the choke, but the low compression can be a big deal. Is there something simple I can do to try and see if I have a stuck piston or a bad seal or am I looking at a total motor rebuild?
 
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