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Constant Alarm 1999 VMAX

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Vampire69

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I have a 1999 Yamaha VMAX 175hp. I have a constant alarm as soon as I turn on the key. If I energize the fuel enrichment valve the horn will drop significantly in volume but I can still barely hear it. If I turn the key off and then back on, I will have the loud horn again unless I power the fuel enrichment valve again and then it again goes to being barely audible. The engine does not go into any kind of limp mode when the horn is going off. Any ideas?
 
In my Yamaha experience, alarm upon key turn is related to low cranking battery volts. The other immediate alarm trigger is low oil or the oil sensor firing a false positive due to bad conductivity within the oil harness.
 
I found the fuel enrichment valve by accident. I was turning key on and off and pushed in the key to the prime position. To be honest, if I could find another way to momentarily cause a drop in voltage, it might do same thing. I have disconnected the thermal switch input and it did not stop the alarm. I have disconnected the oil level sensor from the main oil injection reservoir and it did not stop the alarm. I pulled out the oil level sensor unit fron the aux oil reservoir and flipped it upside down to simulate a full tank condition and it did not stop the alarm. When I purchased the boat used, the power head had been rebuilt, but they left the line powering the alarm unplugged (because it was sounding constantly I assume). I could leave it unplugged but I would like to have the protection of the overheat alarm
 
Docksidemarineservices said:
Fuel enrichment valve has nothing to do with your alarm.....

Your oil system is having an issue....
Click to expand...

Agreed. Troubleshoot by volt drop testing from tach to reserve tank to main tank. Time consuming, but that’s the only option other than replacing sensors and oil harness which ain’t cheap. The issue is likely the ground, as it’s usually the culprit of conductivity issues.
 
Vampire69 said:
When I read the voltage to the wire for the alarm, I am getting 8.7 volts. Ground problem possibly?
Click to expand...
Where is you ground test lead being applied?

If the test lead is to a good ground and you are only seeing 8.7 volts on your meter then that is voltage drop. Excessive voltage drop. Find out why.

If you have low voltage to the warning horn, what about the voltage to the ECU? Low voltage can cause the warning horn to sound in some models. See post #2.
 
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