Suzuki DT 3.5 outboard that will not idle... ideas?

[MagicalArmchair]

Hello all,

I own a Suzuki DT 3.5 outboard (circa 1980s perhaps?) that looks in fabulous condition however it will not idle. After lots of tugging with the choke out, it will idle, just, with the choke half way out (even then it will die eventually). You can roar around to your hearts content at full throttle with the choke pushed in, however, as soon as you idle (or get close to it), the engine dies.

I have done all of the obvious things, such as look at the idle jet, clean up and soak the carb and generally clear out anything that looks vaguely like a jet. I've changed the fuel, which was pretty ancient (it contained water and too high a ratio than the 50:1 the engine needs as the fuel had clearly evaporated over time and left the oil behind), but the problem is no better.

All this leads me to four questions:

• Does anyone know what the points gap should be on these motors?
• There are four timing marks, one at top dead center, and three clustered together. Does anyone have any advice on doing the timing on the beast?
• Does anyone have a workshop manual they could scan for me? There are lots of parts manuals online in PDF form, nothing that gives any practical advice.
• Does anyone have any other idea to try to get this venerable old beast transporting my family about safely?

As ever, thanks for your assistance.

Mark

 

[VicS]

Hello all,

I own a Suzuki DT 3.5 outboard (circa 1980s perhaps?) that looks in fabulous condition however it will not idle. After lots of tugging with the choke out, it will idle, just, with the choke half way out (even then it will die eventually). You can roar around to your hearts content at full throttle with the choke pushed in, however, as soon as you idle (or get close to it), the engine dies.

I have done all of the obvious things, such as look at the idle jet, clean up and soak the carb and generally clear out anything that looks vaguely like a jet. I've changed the fuel, which was pretty ancient (it contained water and too high a ratio than the 50:1 the engine needs as the fuel had clearly evaporated over time and left the oil behind), but the problem is no better.

All this leads me to four questions:

• Does anyone know what the points gap should be on these motors?
• There are four timing marks, one at top dead center, and three clustered together. Does anyone have any advice on doing the timing on the beast?
• Does anyone have a workshop manual they could scan for me? There are lots of parts manuals online in PDF form, nothing that gives any practical advice.
• Does anyone have any other idea to try to get this venerable old beast transporting my family about safely?

As ever, thanks for your assistance.

Mark

I dthink still a blocked jet in the carb.. See the last post in this thread on iboats http://forums.iboats.com/yamaha-suz...dt3-5-running-problem-258601.html#post2056842


Cant help with the points gap or the timing marks. Perhaps ask on the Yamaha /Suzuki board on the iBoats forums

 

[rogerthebodger]

I had a similar fault with my DT16. I changed the crankshaft seals ,which had gone hard and not it will idle once I get it started.

 

[MagicalArmchair]

Thanks for all your help, I will post on iboats too and have a look at the crankshaft seals

 

[macd]

Thanks for all your help, I will post on iboats too and have a look at the crankshaft seals

It could be the crankshaft seals, but the most common symptom of that is revs rising independent of throttle opening (air is drawn in from where it shouldn't be, weakening the mixture: not good news because it could cause detonation).

 

[seumask]

Change the Spark Plug, simple and cheap and one to be done early on the list. Believe it or not had similar symptoms on a Mariner 3.3 and it was the Spark plug. I now carry a spare inside the cowling and its always available for a quick test! so to speak.