Merc 150EFI - intermitten overheat alarm - HELP!!!

[misterbass]

I own a 2002 Merc 150 EFI and run it on a Skeeter SX190, and for the last three seasons (including 2008) I have had an intermitten problem with the overheat alarm sounding. In the beginning it happened only while getting the boat on plane (hole shot) and would go into Guardian mode. After sinking $2,000.00 into the motor including repalcing the waterpump (impeller), thermostats, sensors, and most recently the Alternator. The most recent work the mechanic diagnosed a power surge from altenator which burnt out the key switch and voltage regualtor (built into altenator), and replaced both. I contacted Mercury and they think it could be a harness issue! Does any experienced Merc techs have any ideas or advice before I sink any more money into this wild goose chase????? Any help is appreciated!!!!!

 

[bashields]

Re: Merc 150EFI - intermitten overheat alarm - HELP!!!

Not sure if you are aware but that alarm is also for low injector oil on the right side of your motor under the cove there is a small resivior that is filled by the main resivior if it get an air bubble or low on oil just by an inch or so the alarm will go off. I have a 2007 150 efi and if I let the main tank get bellow 1/2 full and I'm out in chop the resivior sometimes burps some air and the alarm goes off. take the cover off start the engine and open the little cap on the oil resivior untill it fills with oil and all the air is purged. Screw the cap on tight as it will leak all over the motor also make sure the big holding tank cober is sealed tight.
All this is provided the engine is not really over heating.
Regards
Angler Management