Overheat alarm going off 85DT

[jrlat]

1987 Suzuki 85DT. The motor runs and drives great up to about 3/4 throt. Than the alarm sounds. I can shut down and start back up immeditly and alarm is off and runs great at anything under 3/4. I have changed impella and has good water flow. I tested the thermostat and that appears good. I have looked at alot of past threads and there is much talk about a waterflow sensor. I have the manual for motor and can not find one. What I do have is a heat switch located between the 1st and 2nd spark plugs and there is a combination valve under the cylinder head for water flow. Could one of these be bad? Any help would be great.
Thank you

 

[circle hook]

Re: Overheat alarm going off 85DT

do you have oil injection check the level sensor also, these two things can put your engine in protection mode and the engine will not rev over 2,000RPM on my engine ita a 90HP yamaha I disconected the pink wire and now the engine revs all the way to full throttle, but now the protection alarm now does not work. but make sure also the engine is not over heating. good luck Bob

 

[jrlat]

Re: Overheat alarm going off 85DT

I can check the sensor and see if it is sticking or try to unhook it for a short run. I know this motor will run at 3000 to 3500 rpm with out the alarm going off. I was also wondering if it is possible to cause the engine to run hot if the carbs are not set right. I rebuilt them so I could have messed them up. First time

 

[stylesabu]

Re: Overheat alarm going off 85DT

were you having a problem with overheating before carb work? if not then start by looking at spark plugs, a lean cylinder runs hotter, this could be a problem. t-stat you said it looks ok. you can't tell if a t-stat is good by looking at it.there is a number stamped on it, this is the temp its supposed to open at. boil test it,pan of water of stove with a thermometer in the water see what temp it starts to open at, there different heat ranges so start at 155 others go as high as 180, but they open much sooner than a car t-stat.