No "switch on" alarm on Mercury 150 EFI

[ninearrow]

Am looking at buying boat with 1996 Mercury 150 EFI. I previously had a boat with this motor and it performed well.

The seller of the boat I am looking at has owned the boat since new. He said that 2 years ago, alarm sounded and motor started running rough. He took it in and was told the oil injection pump had stopped working. Technician recommended he remove the oil injection and mix the oil when adding gasoline. He agreed to this and oil injection was disabled or removed. Oil tank is still there. He said motor has performed well since then. I understand this is often done on these engines and that some owners prefer this as a sure way to know that motor is getting oil.

My concern is this: When I turned the ignition switch one notch to "on" (not crank) position, I did not hear the short beep to let me know the alarm system was operational. With my previous 150 efi, I always heard a short beep when turning on the ignition switch. I understand the alarm is not needed to warn of lack of oiling if the oiling is disabled and fuel and oil is mixed.
However, I do want to be sure the alarm is working to warn of engine overheating.

How can I be sure overheating will sound an alarm?

And, how can I be sure the alarm is working every time I start the engine?

And, should I be nervous about buying a 96 model engine that has the oil mixing disabled and no start up alarm?

Any other advice for what I should look at on this engine before buying would be appreciated.

Thanks.

 

[BIGFLAT]

Re: No "switch on" alarm on Mercury 150 EFI

Mine does the same thing since my oil injection was removed. Seem to remember a beep beep when I turned on the key. Been mixing for quite a while. Lost a V6 135 from a failed oil injection system..BF

 

[speed4]

Re: No "switch on" alarm on Mercury 150 EFI

The horn isn't beeping because the oil mixing/injection has been removed. I would bet, the oil alarm module has been removed. This is what makes the testing beep in the first key position.

oil injection module pics

without oil module

Follow the overheat sensor (starboard side head) wire to the place where the wire lands, should be upper starboard side of the engine. You will see a few 2-4 wires screwed into a ground point on the powerhead.

overheat sensor pics

where the wire lands

You can test the horn beep by jumping a wire from that wire landing point to ground.

Now this won't test if that sensor is working, but it will test if the horn does beep.

You would have to heat that sensor to the point where it would close (complete the circuit) and put your ohm/resistance tester on it.

I just removed my oil injection yesterday, I like the idea of it, I just didn't want to be caught without it working. On a 1983 motor that spends most of its time at WOT, I didn't want to take a chance of it failing.

The main thing I do when buying a used motor/boat would be a good long on the water test. Just hooking it up the hose in the driveway won't well you anything. You need to get the motor hot, run it at all rpms and make sure everything is good. Look at the water pressure (hopefully there is a gauge for it).

jeez, I hope all this makes some kind of sense. it does in my head!

~mike

 

[ninearrow]

Re: No "switch on" alarm on Mercury 150 EFI

Wow! Mike, great answers with pictures and everything.

Should be very easy to test the horn.

Plus, I absolutely agree with you that best test is on the water at different rpm and simulate how boat would be used in everyday fishing.

Thanks so much.
ninearrow

 

[Check85]

Any pictures still avaliable??

goin thru same situtaion

 

[GA_Boater]

Any pictures still avaliable??

goin thru same situtaion

This thread is from 7 years ago. Please start a new thread so you can get help from active members unlike all the ex-members who posted in this thread.

Closed.