Continuous alarm when getting on plane

[jamsdad65]

Good morning I have a 2006 Mercury Optimax 150HP on a nitro bassboat. I have had recent problems but only on occasions of getting a continuous alarm when getting on plane. It seems to happen with a full livewell when the boat takes a bit to get on plane. As soon as it starts to level out the alarm will go off. This problem has also happened in rough water idling a bit then launching, then the alarm will go off. It seems to me like maybe the float is getting stuck someplace in the oil tank mounted on the engine. Any ideas?

 

[Texasmark]

Merc uses a thermostat for cooling below 2500 rpm and a bypass "popoff" valve for rpms above that. The bypass is larger in area allowing more flow for the cooling requirements of higher rpms. If the water is cool enough the stat will close back (143F opening temp) and only the popoff allows water flow through the powerhead. I'd say that either your water pump, aka impeller, or your popoff aren't functioning properly. If your impeller is over a couple years old, suspect it first. If operating in salt water the popoff could be suspect also. On a similar engine the "feed" to the popoff comes from the top, center, rear of the block, a black hose that routes down to the base of the block just above the cowling where you should find the popoff itself.

On your engine if you are having a solid alarm OT fault it means that one of the banks reached 195F. If you are having a 101010101 type fault it's oil related.

 

[jamsdad65]

Thank you. I guess I need a computer to pull the codes out of it. Will try the easiest first and see what happens.