1990 evinrude 150xp unusual warning tone

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Brian121804

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I have a 1990 evinrude 150xp and I have a strange warning tone I need help with. The tone will sound one short tone about every 2 - 10 minutes. It has plenty of water pressure oil tank is full and the motor is running perfect. I know it has a low oil alarm the is one short tone every 20 seconds but this one is one short tone every 2 up to 10 minutes apart. It doesn't have any certain time it does it but never gets closer together than 2 minutes. And it does it at an idle and running wot. I really hope someone on here can help me?
 
I've heard of things like this happening before but have never experienced my self. Pull the hood off of the motor and check the oil reservoir on the motor. Sometimes because of rough water or bumpy road conditions an air pocket or bubble will be created that will trigger the low oil alarm every now and again. This might not be the problem it's possible that there is a bad censor on the motor. I'm not an expert but if all else fails take it to a good mechanic.
 
Is there a reserve tank under the cowling? I know there is a tank inside the boat but not aware of one on the motor.
 
Check the oil tank on the motor & make sure it's full. If you see two stroke oil pooled up or every where then you either didn't have the lid all the way tightened or it has a crack. Note on most older two strokes of that era there are no fancy electronics to shut the motor down if you run low/out of oil only an alarm to tell you that you are low on oil before the motor burns up. If the oil reservoir under the cover is full then I would bet you have a censor of some sort going out & I would consult a good outboard mechanic about getting it fixed. If the reservoir is low check for cracks or that the lid is on tight; if no cracks are found & the lid is secure simply re fill with oil as this was most likely caused by an air pocket triggering the low oil alarm.

The best of luck ccm.
 
Tank is located inside boat and yes its full. It actually supposedly does have the shut it down feature on it. Like I said supposedly cause like you said motors from that era usually don't so I'm not going to depend on it working.
 
Yup exactly what I thought too. Now just to find out which one and how much to fix it.
 
You have several sensors on the engine.
All are connected in through the TAN lead on the back of the horn.
Troubleshooting which sensor is setting off the horn is fairly simple.
Disconnect one at a time and figure out which one makes the horn quit sounding.
On your engine you should have tan leads from each cylinder head.
Tan lead off the fuel/oil injection pump
Possibly a high fuel vacuum switch with one on it (depending on if that year had it or not).
Oil tank tan lead.
Second possibility is a bad horn. Have replaced several of that vintage.
Third possibility is a low voltage spike to the horn which would make the horn "think" you had momentarily shut the key off and it is doing a self test when the voltage comes back up past the threshold voltage required to latch the system on. You can connect a voltmeter to the back of a gauge while running if you don't have a voltmeter in the dash. Typically I see this when somebody is using wing nuts on the battery. Connection will be loose and occasionally breaking contact. This is a high amperage charging system and can sustain damage from loose connections. If this is the case go buy some locknuts and do the job right.
 
Yes I believe my motor does have all the sensors you mentioned. I was also thinking I could unhook them one at a time to trouble shoot them. I do have large stainless nuts on each one of my batteries also. My first orginal thought is if it was a horn or sensor going out it should do it without motor running as long as the ignition is in the on position. So the first thing I did after fishing Monday was turn it on but not start the motor. Let it that way for over 30 minutes and not one single warning alarm other than the self check.
 
The most obvious of the old style horn failures is that they will come on very softly and stay on. Those are the easy ones. Apparently while running, with the increased voltage there must be some kind of bleed across the circuit board. Years of moisture or whatever.
Anyway....go through the steps mentioned and see what you come up with. If nothing....replace the horn. They aren't cheap.
 

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