Random Overheat alarm

[holata]

I have a 98 merc 225 EFI.... New water pump, Fresh rebuild etc. It has given me an overheat alarm a few times (within the last 80 hours of operation) it has happened during Idle, WOT, and half throttle... if I shut the boat down and wait for a little while it will go away and run great for another 2weeks or so then do it again for apparently no reason!??? Plenty of water pressure, Pees good...

Water Poppit?
Bad sensor?
Running lean sometimes?

What do you think?

Has anyone ever seen this before?

[hsbob]

check the poppet [ i think the 3.0 still have them]. that could explain all but the idle. the pee volume is not a good indicator of over all volume.

[holata]

I have a simons water poppet diverter.... everything seems to be ok with that... it opens up a spews all kinds of water right around 2500 -3000 rpms

[holata]

I put a new set of plugs in it and made about a 3 mile run...

Pictured is the #1 plug (on the left) and #2 plug.... the 1,3,5 side of the motor has the dry tan appearance while the 2,4,6 side has no brown and a Slightly "wetter" look


any ideas?

[Specialized P4-12]

r u sure it is the overheat alarm.. cuz it could just be an engine alarm and u could need TPI sensors.. had it happen..

[holata]

it is a constant beep with no pauses

[Specialized P4-12]

yup.. u need to put it on a computer.. it will tell u right away what the code is.. the tpi sensors are conected to the throttle and should be right above the vapor seperator/fuel pump area.. two little square boxes that have disconects on them.. should be an inside one and outside... one for each bank.. my motor was a 99... im pretty sure u should have them.. and thats what made my alarm go off intermitently and when i shut off the engine and started it righ tback up alarm would be off.. tpi

[Specialized P4-12]

they arnt cheep...