1995 150HP BLACK MAX ALARMS

[imported_BASSCHASER]

I have a 150 black max that seems to run very strong and have good water pressure and nice smoke trail, but alarm goes off and does not stop. The alarm will stop after the key has been shut off for say 30 seconds. If I start it up again right away, no alarm. If I then take off and give it good throttle, it will alarm again. If I just give little throttle it will go all day with no alarm. What do you think?

 

[ncfish1]

Re: 1995 150HP BLACK MAX ALARMS

Sounds like the poppet (relief valve) is not functioning properly. It provides additional flow of water for speeds above idle.
There are several threads related to this within this forum.
The relief plate is located on the lower starboard side of your outboard and looks like a figure-8.
Not too difficult to replace the internal components.

 

[imported_BASSCHASER]

Re: 1995 150HP BLACK MAX ALARMS

Thanks ncfish1, i have the service manual but it had no suggestions towards that fix. I'll give this a try, and thanks again.

 

[andy6374]

Re: 1995 150HP BLACK MAX ALARMS

What are your water pressure values are various RPMs?

When's the last time you went through the entire cooling system? That is the waterpump, tstats, and pressure relief valve system.

 

[imported_BASSCHASER]

Re: 1995 150HP BLACK MAX ALARMS

MY WATER PRESSURE AT 5500 RPM IS 12-15 PSI. IT RAISES UP NICELY WHEN THE RPM'S RAISE AND THE TATTLE TALE STREAM IS GREAT WITH NO BOILING ANYWHERE. I REMOVED THE SHROUDS WHEN THE ALARM WENT OFF AND THE MOTOR WAS NOT RADIATING THAT MUCH HEAT TO SPEAK OF.

 

[andy6374]

Re: 1995 150HP BLACK MAX ALARMS

Can you keep your hands on the cylinder heads for at least 5 seconds without hurting your hands?

If the tstats stay closed (bad) the overheat switch will flip in no time and you will have good water pressure, but I'd imagine more than 12-15 psi.

If you don't know when the cooling system components were last replaced then the safe course would be to change them out.

Also...could be a bad overheat switch.

 

[ronnieboy]

Re: 1995 150HP BLACK MAX ALARMS

motor should have lots more pressure than 12 to 15, should be in the low 20's 23 to 25, maybe poppet ? good luck ron

 

[gss036]

Re: 1995 150HP BLACK MAX ALARMS

Maybe somebody with a Mercury Factory manual for that engine should try to look up the water pressure for WOT. My 1989 200 Black Max says 12 psi at WOT. I know some have the higher pressure water pump, so that would be one of the first things to find out befor tearing into the engine. I think Andy is right about the thermostats. 12psi will open the poppet valve as they are normally preloaded for 7-9 #, 2700-2800 rpm.

 

[imported_BASSCHASER]

Re: 1995 150HP BLACK MAX ALARMS

I had changed out the poppett this weekend and the impeller was done about two months ago. All looked alright and the cylinder heads can be touched without burning yourself. I am going to check the overheat sensor to see if it is bad. The boat came with all paperwork when I bought it, and it looks as though the previous owner had problems with the module, so I will not rule that out either. Thanks for all the help so far ncfish1, Ron, Andy and Gary.

 

[Cardman12]

Re: 1995 150HP BLACK MAX ALARMS

I have a 95 135 black max that makes a beep beep beep alarm and wont go above 3000 rpm. It went into limp mode i was told. I started trouble shooting things and have replaced the ignition switch, the oil module sensor and the oil float in the resevor on top of the engine. When i disconected the purple wirer on the right side of the engine the deeping stopped which is why i thought the oil module sensor was bad but now even with the new one the deep deep deep alarm under the dash is still going off and the motor is still in limp mode. Any other sujestions to what the problem is and how to fix them would great thanks

 

[j_martin]

Re: 1995 150HP BLACK MAX ALARMS

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