Water temperature sensor

[Tricky1]

I have an 2001 150 Yamaha oil injected two stroke on a Hurricane deckboat.I am having problems with it fowling plugs.Have rebuilt the carbs and the engine runs great throughout all throttle ranges.Has new themostats.Before I replaced the thermostats heads were cold to touch.Now they feel warm so I think it is running at proper temp.In my Yamaha service manual it shows an engine cooling water temperature sensor but no explanation of how it works. Could this be somehow causing my problem?It isn't just one plug but all of them.They always look wet even before they completely fowl and cause a misfire. Thanks.

 

[rodbolt]

Re: Water temperature sensor

hello <br /> is this a sensor or a switch? the carbed 150 I dont think had a sensor for temp. just switches for overheat. but I could be mistaken again. I am at home so I cant look it up. anyway also check your fuel pumps. a leaking diaphram can cause this as well. also check the parts bulliten and see if your engine uses fuel recirc valves. not all did. also test the red spark plug caps if your motor has them. unscrew them if they are red and test them with an ohmeter. should be about 5kohms.<br /> check the oil link rod is correct and the clip is intact. and check the hood and airbox for obstructions. <br /> if the problem persists post back and we will hunt some more<br /> good luck and keep posting

 

[Tricky1]

Re: Water temperature sensor

Hi Rodbolt<br /><br /> This engine has a temp switch at the top of each head which I believe control the alarm.I bought the Yamaha manual and it shows a temp sensor near the bottom of the right cylinder head.I cannot actually look at the engine until tomorrow to see if it is there.I was studying the manual when I saw it on the schematic.I guess it's possible the manual covers several models and mine does not have it.I have replaced both fuel pumps and adjusted the oil link rod which was about 1/4 inch shy of returning to the stop pin .Is it possible for an oil pump to be pumping too much oil? I will test the plug caps tomorrow and check intake baffle.I did notice that the float height in my manual said .63in and they were set to about .75in. I reset them to what the manual said which would make the fuel level higher.Can you check the specs.

 

[rodbolt]

Re: Water temperature sensor

hello<br /> for the specs I must have your model number. the other thing I have seen is the pump shaft seal will sometimes fail. its rare but it does happen<br /> check everything else but .65 plus or minus .02 sounds about right<br />good luck and keep posting

 

[rodbolt]

Re: Water temperature sensor

hello<br /> well I checked my quick reference guide and it shows the 01 150 has a sensor as well as two switches. the sensor has no affect on carbs just timing at warm up. I will look up the other specs if I go to work tomorrow

 

[Tricky1]

Re: Water temperature sensor

Hi Rodbolt<br /><br /> I think I found the problem.Went out today to check the resistance on the plug caps-they were fine at 5k ohms each.I took the air silencer of and found a lot of gas in it.I squeezed the fuel bulb and noticed gas squirting out of the float bowl vent tube on the left side of the middle carb.I looked really closely with a magnifying glass down in the needle seat and it looks like someone might have been scratching around in there before me.I am thinking that might be why the floats were set wrong-they were trying to compensate for fuel leaking by the needle and seat.Am getting another float needle and will try again.I don't know what I can do about the scratched seat area I will post back and let you know how I make out.<br /><br /> Many thanks for your help!