1993 Suzuki 2 stroke DT85: idling motor cuts out under forward power?

[John McDonald]

Frustrating issue out of the water the motor generally does NOT cut out, however in the sea the problem occurs?
I have studied workshop manual which pointed to the '37810-95D05 - SENSOR,THROTTLE' which I have replaced, unfortunately no difference, I have stripped down and checked the 3 carburetors they seem fine, I have replaced the 93 octane fuel. Pulling my hair out with this issue, any thoughts would be greatly appreciated.
Thanks
John

[Solarman]

Idling problems are generally related to carb problems. Most problems idling occur from blocked fuel, or air passages, or jets. If the carbs and jets have been soaked well (in a carb cleaning solution), then each tiny hole/passage is blown out thoroughly using compressed air (don't ever use wires in these holes or passages), then carefully putting carbs back together, resetting float settings, and resetting all 3 idle air mixture screws identically to the service manual setting. Making sure you don't mix up parts between carbs (some older carbs had different jets between top, mid, bottom carbs), you should be back to how the factory originally set the motor up. When using compressed air to blow through all of the passages use a clean white rag ro wrap the carb to catch any small trash that comes out, this might help identify where/if something (fuel lines, low pressure pumps-disc valves-diaphrams, or trash from stations you purchase fuel from) else is needing to be inspected/ replaced. Once everything is back to how the factory set it up, then if the computer (gear counting coil/ throttle sensor), compression, reed valves, oil mixture and plugs, are all good, you'r idle should be controlled properly.

Good luck, post back on what you find out.

[John McDonald]

Hi Solarman,
I think I have solved the issue? I followed Fuel / Air mix settings from Manual 'Suzuki DT75 / DT85 oil injection Service Manual (99500-95521-01E) whereby it states normal Idle Speed Fuel / Air Adjustment for my 1993 DT85 settings should be set 3/4 - 1-1/4 (Section 3-7). THIS IS NOT CORRECT, Referring to a different Manual, it tells me that the 1993 DT85 has a different setting to other DT85 motors, the Manual I am referring does not appear to have a model number reference but has 'Master Index and is just under 400 pages and refers to numerous Suzuki sized motors, on 'Carburetor Idle Air Screw Specification Maintenance page 3-33 DT85 it shows the 1993 Motor settings should be 1.375 - 1.875 turns. So changing ti these settings has definitely improved the issue, also found the Throttle linkage was NOT in sync with the 3 x Carburetors, also the Throttle Sensor Switch was not set to specifies 0.5v it was reading 0.35v, so after resetting all of these to their correct settings the motor has greatly improved, however I want to take the boat into the water again just to make sure. Many thanks for your help.

John McDonald