Alarms sounding when key is turned

[Weedy]

Hi guys, hope all is well in the boating world for ya! I have a 95' johnson 150hp, that I was running the other day at about 4200 RPM. The overheat alarm went off and it shut down to 2500 RPM and wouldn't go over it. I let it idle for about 5 minutes to cool it down, all the while the alarm still sounding. I had good water flo thru the weep hole on the back of motor the entire time. I pulled the cowl and the heads were not any hotter than normal and there was no burning smell like it had over heated. I idled back to the dock (about 2 miles), put it back up on the lift and flushed it out with fresh water as usaul. My problem now is that the moment I turn the key on the alarm sounds (consant, no break in sound) and it will not go off, also, it still won't shut off! Need help, not sure what is the problem and I really do not want to spend the $$ and take it to the shop and spend the big bucks to have them tell me whats wrong. Thank you in advance for any help that I can get.<br />Thanks<br />Weedy

 

[WillyBWright]

Re: Alarms sounding when key is turned

Welcome to iboats.<br /><br />I'm not sure what year System Check came out. If you have it, there will be a 4-light gauge (maybe built into the tachometer). When you turn the key on, the horn beeps and the lights light-up and go off one at a time. If you have this system, it could be a bad gauge which sends the signal to the horn.<br /><br />If you don't have the System Check Gauge, the alarm horn itself might be bad. There is circuitry inside those that performs a self-test. It's designed that if it detects a defect, the horn will sound a steady tone.<br /><br />You could also have a bad overheat sensor which is rare, or a short in the wire leading to the horn which happens sometimes.

 

[Weedy]

Re: Alarms sounding when key is turned

I believe systems check came out in either 96' or 97', anyway, it is not a systems check motor. I figured it was either a short or a bad overheat sensor or short. The horn going bad I could understand, however, I don't think that it would shut the motor down to 2500 rpms. Thank you for your input WillyBWright.<br />Weedy

 

[Joe Reeves]

Re: Alarms sounding when key is turned

Overheating and having the warning horn engage would enable the S.L.O.W. system which would knock out one bank, dropping the rpms down to the 2500 rpm you mention.<br /><br />Running the engine for 5 minutes at any rpm, waiting for the engine to cool off and the warning horn to disengage is not a good idea.<br /><br />I'd strongly suggest that you drop the lower unit to inspect the water pump assy.

 

[Rastus P]

Re: Alarms sounding when key is turned

For those folks with old eyes like mine strap on your reading glasses, this is gonna take a minute.<br />I'm having this same problem. Started before I discovered a scored cylinder. I have replaced the powerhead, rebuilt the water pump and overhauled the carburetors, And lo and behold, when I turned the key to check out the wiring I got the continous alarm(the very 1st two times I touched off the starter all I got was the short test beep). Since the motor has not yet run it is not a temperature issue(but I checked the temp sensor during the teardown-no problem) I checked out the blocking diode no problem. However I discovered that removing one of the wires from the oil sending unit caused the continous alarm to cease(the initial test beep still occurs?) My shop manual states that the oil sending unit should only cause pulsating alarms not continous?(and yes the Vro tank was 3/4 full. Removed the sensor and played with the float while watching the ol' meter no change. Since the motor is not running would a defective vacuum switch at the Vro pump cause the constant alarm? if so why would disconnecting the oil sending unit stop the racket and still allow the horn to appear to work? Any ideas mr. Reeves?