2014 BF90 D2 overheat warning on quick deceleration only

[58panman]

My 2014 BF90 is alarming overheat on quick deceleration, from about 28 mph for 1/2 hour. I believe I have a separate issue as then the ignition switch won't crank the engine after it shuts down on the automatic shut down ( I can use a screwdriver to go from ignition to battery at the solenoid) it starts back up and is fine. Got to where I needed to be about 10 miles, shut it down, had lunch. Tried ignition switch and it started. Same thing on my 20 mile trip back. Actually replaced ignition switch as it was not returning all the way from crank position. Tested wiring from ignition switch to the solenoid shows good. Did wiggle test, no intermittent loss of connection. I have a manual on order, is it possible that when I slow down fast I noted the tell tale is under water for a short time. Could it be that tell tale under water with possible cavitation is not allowing cooling for a few seconds? Is there a cutout of crank power for a while when this happens, like a delay relay (I doubt it). I have many years experience in the automotive, motorcycle, semi, heavy equipment etc. field. Boats aren't really any different mechanically, but I thought there might be something at least with the tell tale being under water that I'm not familiar with. Thank you in advance. In the meantime I'll search online in parts diagrams for a delay relay.
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[racerone]

Tell tale under water has nothing to do with it.----Have you installed a new water pump impeller ?

 

[58panman]

No, cools fine at full speed and when slowing down slow, fine at idle. Only while fast slow down do I get the warning.

 

[racerone]

Motors need a new impeller about every 5 years.

 

[58panman]

I have replaced them before, what is your theory why it is only affected on a fast slow down an no other time?

 

[58panman]

I ordered one incase it's slightly hard and at higher rpm's won't cool as well.

 

[jgmo]

Hi,

This is definitely an odd set of symptoms. The tell-tale underwater shouldn't make any difference as racerone already said.

This sounds like an electrical connection problem to me.

If it were mine, I would start by inspecting and cleaning each electrical connection I could get to. Starting with the battery cables.

I've seen the ends of battery cables actually snap off but be still barely making contact.

Everything works until there's a turn, stop, hard acceleration or the engine torques.

That small amount of movement causes the already poor connection to part and trouble happens.

This same scenario can happen with a very loose or corroded connection.

The reason things come back online and start working again is because wires and cables have a bit of "memory" and will often move back to where they were before...especially as temperature changes.

Pay close attention to grounds. They often are the most neglected, corroded and are usually a bit harder to reach. But well worth the effort especially on a boat.

If you have a 1-2-Both battery switch, give particular attention to that. Those are often the source of problems.

Good luck.