Yamaha 130 Temp sensor issue

quikstang347

Seaman Apprentice
Joined
Jan 22, 2009
Messages
31
Model # S130 TLRU

Recently i had an issue with the oil injection and have rectified the issue i am sure this is a temp sensor problem.

Ok here it goes while running the boat at 4200 + rpm's the alarm would sound and the motor would go into limp mode, so i have begun my investigations. i pulled the sensors and checked them they work and show open and closed circuit with heat. the issue is they open at 120 degrees and set the alarm. so i left them hooked up to the engine hit them with a lighter and as soon as they hit 120 degrees the alarm sounded. this happened on both sensors. i then water tested the boat at full throttle 5700 rpm and trimmed properly the engine runs fine with the sensors removed from the head and just hanging. i did bring an infrared temp probe while moving i checked the head with the temp gun and at low rpm it runs about 122-125 degrees and at wot it runs about 155-160 max. plug the sensors in and waaalaa the alarm is back and so is rpm reduction. some of the repairs i made were .
pulled heads and descaled the water jackets
changed impeller
cleaned the poppet valve
changed thermostats
changed all gaskets . there is no leaks and compression is even at 140 across the board
the tell tale has a great stream of water and it is not hot
water seems to circulate and cool properly
the motor seems to run perfect with the sensors pulled. they are operating and the alarm system is doing as it should i do not believe that at 120 degrees the engine is overheating at all . i also believe that 155-160 is a good operating temp and should mean that al cylinders are firing and motor is running good. is it safe to say i should buy new sensors , i am not into spending money on parts for the hell of it . Any advice would be helpful.
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,842
Re: Yamaha 130 Temp sensor issue

What does your service/ repair manual say about the operating temp of the temp switches? MY c40 has 2 and they operate at different temps doing different things
 

quikstang347

Seaman Apprentice
Joined
Jan 22, 2009
Messages
31
Re: Yamaha 130 Temp sensor issue

says they operate at 180+ degrees one sensor for each bank . but they are sending signal at 120 degrees . I believe them to be faulty.
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: Yamaha 130 Temp sensor issue

if they close at a verified 120 degrees they are faulty.
they should close about 183 and open about 165.
carefully test the temp inside the switch pocket.
its on a blind passasge and can get very much hotter than the block if the passage is plugged with something.

only way to clean the passage is removing the head.
 

quikstang347

Seaman Apprentice
Joined
Jan 22, 2009
Messages
31
Re: Yamaha 130 Temp sensor issue

Hello Rodbolt and thank you for the reply,
I did do the test already and temp probed inside the pocket where the sensor sits and it is 155-160 at full throttle on both banks, I have done a total descale and removed the heads already. I tested the sensor with a lighter and an ohm meter and they open close at 125 degrees. i did also check it with a pot of boiling water and same thing. I also used a mercury thermometer to make sure my temp gun wasnt off and a dvom with a temp selector and everything was right on . i also tested the heat of the head and it is even across the board , the heat is even on both heads . the bottom of the head is a lil cooler, but probably due to thermostats being up top. i believe i have tested every area and will go get some new sensors this weekend. the last test i did was i hooked everything up and the sensors were left out of the pocket . i hit them with a lighter and the moment the lighter hit the alarm sounded. i kept the probe on the sensors at the same time ad it read roughly 125 degrees , thanks for the replies, i am trying to get all the lil bugs out of this boat that i bought . seems to be all wiring problems so far and i did alot of unneeded work but i guess it is good to know it has been done and to learn something in the meantime is great m, again thanks to everyone.
 
Top