Boat Overheating - '94 Sport Nautique

Payton,
Before you condemn the sensor, I suggest using an IR temperature gun to check exactly what the temp is. Aim it next to the sensor. Also, for checking proper cooling, I suggest getting it off the garden hose. The pressure from the hose will give you false results. Stick the suction hose in a bucket of water instead and use the garden hose to fill the bucket. Also, you may be sucking air but a water leak won't show up even with the engine shut down. Double check all your hose connections and the gasket on the sea strainer.

Here's a link to a 93 manual from the reference section with ProTec info in it.

Your 94 Pro Tec system is the same as the 93

link

KENO wrote: One thing you should know is that there is no hi temperature shutdown associated with your ProTec TBI system. If the high temperature switch is activated the engine will go into "Limp Mode" and be limited to a max of about 2500 rpm, so if your engine is shutting off, it's for some other reason. Low oil pressure will also put it in "Limp Mode" but there is nothing that will automatically shut the engine down

I observed the light go on and the boat quit at the same time more than once. I should add that it has plenty of fuel.

You have the switch and sender labeled right.

Disconnect the temp switch and it won't go into "limp mode" or cause anything else to happen.

Maybe in the last 24 years somebody did some "creative wiring"

Thanks for the help everyone. I will be purchasing some new components and troubleshooting stuff.

I am still looking for a theory on why the motor stalls.. I will connect the raw water hose directly to a bucket and let idle with an IR gun pointed near the temp sensors. Hopefully I can confirm the temp stabilizes and the temp sender/gauge is reporting the right value. If all is good but it does stall and/or the limp mode light comes on - I'll try to maintain idle again after disconnecting the temp and oil switch.

First of all 160 is far from overheating.

It is my understanding "limb" or "limp" mode limits RPM to 2000.

If you are already idling (presumably below 2000 RPM) lump mode will not affect engine RPM.

Something seems very off if the temp gauge shows 160, or even below, but the temp alarm light is also on. Is the light triggered by the ProTec switch/circuit and not part of the gauge? That would make sense as jimpsport has mentioned.

There is still no reasonable explanation for the engine dying.

The red indicator light in the middle of the dash is a warning light for overheating or low oil pressure. Not related to the ProTec.
You do have oil in it right?
The ProTec will go into limp mode over 2000-2500 RPM......it does not light up the warning light on the dash.
Should not be showing “overheating” at 160 degrees.
That is why I suggested the oil pressure sending unit.

I might have a theory for ya

We'll start out by saying again that there are no automatic shutdowns.

And we'll say that the light on the dash gets input from 2 places to turn it on.

One place is coolant temperature and the other is oil pressure. Either low oil pressure or high coolant temperature turns that light on when the ignition is in the Run position.

And we'll say you did a good job on the impeller and you have no cooling issues

So you're sitting there idling the engine for quite a while and it suddenly quits and your red light is on at the same time.

This is because the key is still in Run and you have low/no oil pressure real quick since the engine just stopped spinning. (Ignition loss for whatever reason till the low oil pressure setpoint is reached is well under 1 second when the engine is idling at 6 or 7 hundred RPM. Or in other words for all practical purposes they happen at the same time.

You then turn the key OFF and the light goes off because you took away power to that circuitry

Then you do it all over again only it happens at a different temperature, but why?.

I think it's shutting down for some unknown reason right now, after all it is a Pro Tec system and you said something in another thread about "how great your Pro Tec system
was running"
You cursed your engine when you said that

Maybe you can sit there and see the light come on for a few seconds before the engine turns off or maybe it's simultaneous like I mentioned above, only you know that answer right now.

You can sit there with it idling and turn the key to OFF and easily see how quickly the engine stops(and the oil pump stops too). You won't get the red light doing this though because you took the key to OFF

Maybe I'm out to lunch (well I am headed to Taco Bell as soon as I'm done typing) but remember there are no automatic shutdowns unless you have some really screwed up rewiring by somebody

I was thinking something very similar to what Keno just said. It's likely not the overheat causing the shutdown. The only way that could happen is if the engine overheated so badly it collapsed the exhaust tubing/hose.

Damn - time to start a new thread.. I believe the light always came on after it died which would make sense.. So now I have a boat that stalls randomly. Also, the boat sometimes doesn't start well when cold only.. Should I just put new plugs in and wires or get the entire carb/distrubuter kit from Skidim. I want a reliable boat..

Pro Tec is sensitive to bad (loose/corroded) wiring, just like any other piece of electronic equipment.

What I get out of this thread and your bow eye thread is that you just got the boat, maybe complete with some Pro Tec issues as an added bonus but it ran good out on the water and you were already aware of the Pro Tec reputation

It sounds like you were changing the impeller because you wanted to, not because it ever overheated. and then the stalling issues came up while idling on the trailer

I'd put it back together with your original thermostat and run it. Bring friends and paddles or another boat to tag along just in case

You mentioned cold start issues and wanting to change plugs etc. The plugs are cheap, wires not so cheap. See what the plugs look like, they may tell you something or they may look real good. What are the cold start issues?

And Hollywood mentioned checking wiring connections as a good thing to do.

Is your alternator putting out a good 13.5 to 14 volts or so while it's idling on the hose?
Low voltage/bad connections can do funny things like make your engine just shutdown.

So.........don't give up on the Pro Tec quite yet, run it , get some info and then decide what to do.

It shouldn't take 10 seconds to start. I can pump the throttle twice when mine is cold and it fires up and purs like a kitten and it's carburated. After that initial start it fires up just turning the key for the rest of the day.

Payton91 wrote: I made the bucket lake, put new spark plugs in, and put the old thermostat back in. Boat ran absolutely fine. Started cold in about 3 seconds and instantly when warm. Ran for 15min no problem. Temps at switch. Battery voltage while running 13.95V Oil pressure on gauge when hot: 53 psi Temp on gauge when hot: 160F Idled at about 900RPM So WTF?? I am thinking: 1. it was scorching hot outside last weekend so that may have had an effect 2. this one scares me, I did run the fake-a-lake with the water on for a bit while my boat wasn't running - does this cause water to fill up and enter through the exhaust? My oil seems ok but should I drain it just in case?

Don't worry about #2 above, it won't happen

You said your oil looks OK, if there was water in it, it would be a gooey, coffee with cream looking mess.

Now take the boat out for the weekend and have some fun

CCF Excorcism complete!