m70c alarm problem

[realchuck63]

I have a 2000 m70c tohatsu..I've un-hooked the oil injection system for starts..I mix my own oil and gas..I started out having problems with an alarm sounding off at 5000 rpm's with a 19 pitch prop..changed to the correct plugs and got to 5400 rpms before the alarm went off and it also loses power with the alarm..I went to a 21 in pitch prop and now I get top speed and the alarm sounds off at 4800 rpms..anything just under full throttle and i can run all day..full throttle with either prop and I have alarm issues..

 

[TOHATSU GURU]

Re: m70c alarm problem

I'm stunned...I don't know where to start with the possibilites of why and what might be wrong. So, lets just pick the most common first. Replace the water pump impeller with a complete water pump kit and see if that cures it.

 

[realchuck63]

Re: m70c alarm problem

I'm stunned...I don't know where to start with the possibilites of why and what might be wrong. So, lets just pick the most common first. Replace the water pump impeller with a complete water pump kit and see if that cures it.

had a new water pump installed couple months ago..i still use the boat at 3/4 throttle with zero issues..I just want full throttle...New plugs also..

 

[realchuck63]

Re: m70c alarm problem

I'm stunned...I don't know where to start with the possibilites of why and what might be wrong. So, lets just pick the most common first. Replace the water pump impeller with a complete water pump kit and see if that cures it.

i also have had this boat too 3 shops,,they didn't even know the plugs were wrong..i found that online...helped get more power but not full throttle..

 

[realchuck63]

Re: m70c alarm problem

new water pump already in with new plugs..

 

[pvanv]

Re: m70c alarm problem

Is the jack height correct, or might it be a little high?

 

[realchuck63]

Re: m70c alarm problem

my cavitation plate looks too be about 1 inch above the bottom of my boat..So I guess its a little high?

 

[pvanv]

Re: m70c alarm problem

If you have room, lower it an inch or 2 and re-test. You may be drawing air at speed.

 

[realchuck63]

Re: m70c alarm problem

I put a high jacker 6 inch offset jackplate on it yesterday..whiched dropped it about an inch and set the motor back 6 inches further away from the boat and it didn't help..whats the deal with that water senser just under my thermastate..Looks to be like a magnet senser??..What does it sense, over heating?..I'm running a temp guage and it never shows more than 110' degrees..actually cooler at higher rpms..I'm gonna change out my thermastate now..Looks to have some corrisive buildup inside the thermastate housing, inside the motor port behind the therm...is there a way I can break all that up and get a good flush on my motor..I'm thinking breaking it up might clog things internal..??

 

[pvanv]

Re: m70c alarm problem

You may have a water pressure sender as well as a water temperature sender. Either can throw an alarm, and engage the 3500 rpm esg limit. Also, you might have an issue with the prop. Is it a rubber-hub type, or is it a solid SS unit?

 

[realchuck63]

Re: m70c alarm problem

I have the same issues with a 13 x 19 solid alum. and I changed to a 13.2 X 21 rubber-hub type,alum..Only change was the alarm went off at different rpms...the solid prop got me 5300 rpm's @ 34 mph ,anything higher would set the alarm. The rubber-hub gets me 33 mph @ 4600 rpm's...anything higher sets off the same alarm..I only see one senser and its under the #1 plug area..Its a one wire senser looks to be worked off a magnet?..

 

[TOHATSU GURU]

Re: m70c alarm problem

What was the part number of the part they replaced on the water pump?

 

[realchuck63]

Re: m70c alarm problem

I had a local shop change out the impeller and the paper work just seems too be invisable this morning..I am thinking about ordering a complete water pump kit tomorrow from tohatsu..I'm guesing you might be thinking the wrong impeller might be installed?..I'm gonna keep looking for that receipt today and compare it to tohatsu's part #.

 

[TOHATSU GURU]

Re: m70c alarm problem

I'm thinking that a kit was needed, not an impeller. There is no situation, where an impeller alone, would be the correct choice.