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black scorpion check eng light

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Cry.gif hi, me and a mate have recently bought a 97 mal response with a mercruiser black scorpion 315 mpi and have been having a problem with the engine that i am hoping someone might be able to help me with.

the first couple of times we took it out it ran perfect but 2 weeks ago when up on the river, after about 4 hours of running, the check engine light and alarm came on for about 4 seconds then went off, this was when doing about 30mph, we carried on for a bit and it seemed to happen about every few hundred metres, alarm and light on and off, they never stayed on for more than a couple of seconds and they never came on at idle, the eng temp and oil pressure gauges were reading fine and all levels are good.

The river that day had a lot of debris in it like flower petals or something so maybe thats blocking something.

Then last weekend we took it out and all was good for about 2 hours then the same thing, engine light and alarm coming on for about 3 seconds every few hundred metres and this time it seemed to be happening at slower (wakeboarding) speed but still not in idle or just putting along, so that was the end of that day

the sticker on the side of the throttle says only 3 things can set the alarm off, the eng temp, oil press and transmision temp, being as the 2 gauges are giving good readings this leads me to the transmision, either an actual overheating problem or dodgy sensor.

if anyone has any experience of this or advice it would be appreciated as we hope to go away with the boat in a couple of weeks and dont want to run the motor any more with this alarm going off.

I cant seem to find any diagrams of the engine so dont know what switchs are which so any trouble shooting tips would be most handy.

We are in melbourne australia and i wouldnt know where my nearest malibu or mercruiser dealer is that is why i have come to this site, which is great by the way, as is the boat up untill now, thanks again..

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Most people here are stuck with Indmars, but maybe someone can still help. Have you talked with any Mercruiser service centers? You should be able to find engine info on the Mercruiser website, but I know they recently removed some info from it. I'm no longer able to get diagrams for my 1990 engine, but it used to have them.

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If I recall correctly, the alarm sensor and the water temp sensor are actually seperate units. The temperature sensors on my boat (Mercruiser engine package) are light brown wires and the alarm sensor I think is blue. The alarm and water temp sensors are located in the thermostat housing which is mounted on the top front of the engine, the sensors are on both sides of the casting. The other thing to check is to make sure all the sensor wires are tight.

I would check for any debris in the transmission cooler, on the water side first. Pull the inlet water line off (comes from the raw water pump and is a 1.25" dia hose) and check for debris. The debris usually can't get through the trans cooler grid and lodges on the face of the inlet side. I would also check the trans fluid for level and smell the fluid to make sure it does not smell as if it got hot.

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The fact that the gauges all read ok would lead me to believe that 1 - it is the transmission as you stated, or 2 - it is a switch for the oil pressure or engine temp. The switch is usually just a simple on/off thing that feeds the computer, which sets off the alarm. The sensor is what sends the signal up to the gauges. These are two totally separate paths. So, it's possible for your oil pressure to be just fine, but a faulty oil pressure switch can set off the alarm.

IIRC you can remove the lead to the switches when the alarm is sounding and if the alarm goes away you know it's that switch that is raising the alarm. Hopefully someone will correct me if I'm wrong.

I've got a newer Black Scorpion, but unfortunately I just put it to bed for the winter and don't have easy access to it again until April. Wish I could help more.


Edited by mlange
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I don't think it's an option at all anymore. There were a few boats in this area that used to come up every year with Black Scorpions. They were promo boats for Tommy Bartlett's and the Rock Aqua Jays, both of whom were sponsored by Mercury. My boat was a Rock Aqua Jay boat.


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