motor Problems

[Yama225]

I have an 02 V max 225. I am having 2 problems with it right now and have a few questions. After long period of idling the overheat buzzer will sound and the boat will not get on a plane. After trying to get it on a plane the buzzer will quit and boat will run fine. It acts like a plug fouling but why would the overheating buzzer come on? The other problem just started happening the last 2 times I ran the boat, on take off and running about 3500-4000 rpms motor will surge every now and then. After reading up on some things on here I wondered if it may be the o2 sensor fouled up. If it is the o2 sensor is there any kind of simple fix to it such as a shock treatment with sea foam or similar. It may be something else causing the problem, and I am sure you guys can help. Thanks

[Hamfisted]

Is it an HPDI or just EFI motor? Do you have a water pressure gauge installed? If not, I would get one. When the overheat buzzer sounds the motor is reduced to a "SAFE" operation mode wherein the computer kills the middle cylinders spark to lower the rpms and try to avoid damaging the motor. That is why you feel the missing, like fouled sparkplugs, because the computer killed two of them.
You need to investigate why the overheat buzzer is sounding. That's where a water pressure gauge is worth it's weight in gold. Your problem could be the waterpump, the thermostats, or the pressure control valve, or any combination thereof.
Do you have a Racor filter installed in the fuel line prior to the motor? If not, you should. You can pull the O2 sensor and test & inspect it. You should be running Seafoam (or RingFree...) in your fuel tank anyway. But your surging can also be fuel filter or fuel pump related.

-Mike

[Yama225]

It is an Efi. It does have a water pressure gauge and what should it be reading when the motor is turning around 5700- 5800 rpm or wot. or what is safe as far as water pressure. Thanks for the input on the overheating prob. Will get that checked in to and try to figure out what is making it surge. Just one more question, is there any way the surging could be battery related, if the battery has a short in it. Thanks for your help, as you can tell I am clueless in mechanical areas. Oh yeah it does have a fuel/ water separator filter, could this possibly be causing anything?? Thanks so much