alarm on a mariner optimax below 3000 revs

Robert Sewell

Recruit
Joined
Jan 21, 2012
Messages
4
I have a cat with 2 x 115 Mariner Optimax motors. One sounds the audiable alarm and the engine derates when running below 3000 revs. Bringing it back to idle stops the alarm and then it will run if it is set about 4000 revs.
I suspect that it may be fuel pressure but would welcome any comments. It is using the same amount of oil as the other motor and it is not running hot with the water pump working well.

regards Robert
 

aussieflash

Lieutenant Junior Grade
Joined
Feb 5, 2011
Messages
1,004
Re: alarm on a mariner optimax below 3000 revs

What is the alarm for??Overheat,Oil warning.Could just be a sensor.Post year and ser# and someone will help.
 

brandon110

Seaman
Joined
Nov 20, 2010
Messages
55
Re: alarm on a mariner optimax below 3000 revs

take it to a dealer have them hook the computer to it they should be able to give you an answer as to what it is in about 15 min. from there you can decide if its something you want to tackle or have them do it.
 

Robert Sewell

Recruit
Joined
Jan 21, 2012
Messages
4
Re: alarm on a mariner optimax below 3000 revs

take it to a dealer have them hook the computer to it they should be able to give you an answer as to what it is in about 15 min. from there you can decide if its something you want to tackle or have them do it.

I would like to be able to do that but the nearest dealer/service centre has gone out of business and therefore it is a 300km trip. when they were in business they had the computer when they did our last service.
 

Robert Sewell

Recruit
Joined
Jan 21, 2012
Messages
4
Re: alarm on a mariner optimax below 3000 revs

What is the alarm for??Overheat,Oil warning.Could just be a sensor.Post year and ser# and someone will help.

The motor is about a 2005 model with serial number #DT8 16235. I have removed and cleaned the temp sensor and will try it again in a day or so. There is no obvious heating problems and the water pump is working well.
 

aussieflash

Lieutenant Junior Grade
Joined
Feb 5, 2011
Messages
1,004
Re: alarm on a mariner optimax below 3000 revs

Time to buy a manual and a pair of overalls.Time to get dirty.A few guys here know the Optis.I would only guess fuel pump/injectors.
 

brandon110

Seaman
Joined
Nov 20, 2010
Messages
55
Re: alarm on a mariner optimax below 3000 revs

So when you first try to bring it up it gets to 3000 RPM's and alarm goes off bring it back to idle and it goes away then you are able to bring it up to 4000 RPM's and run it without the alarm going off? if you try to get more then 4000 does that alarm come on and cut power or will the motor just not go any faster?
 

Robert Sewell

Recruit
Joined
Jan 21, 2012
Messages
4
Re: alarm on a mariner optimax below 3000 revs

So when you first try to bring it up it gets to 3000 RPM's and alarm goes off bring it back to idle and it goes away then you are able to bring it up to 4000 RPM's and run it without the alarm going off? if you try to get more then 4000 does that alarm come on and cut power or will the motor just not go any faster?

Thanks Bradon, if at 3000 rpm the alarm goes off and the motor goes to limp mode, returning the throttle to netural and then pushing it forward to around 4000 rpm, the alarm does not go off and the motor runs at normal power. It will go up to 5000 rpm with no ill effects and develop full power. Your move !!
 

brandon110

Seaman
Joined
Nov 20, 2010
Messages
55
Re: alarm on a mariner optimax below 3000 revs

what you need to do it while running the motor keep an eye on the battery voltage for that battery for that motor. If the alternator puts out more then 16 volts it will sound the warning horn and bring down the RPM's depending on how bad it is overcharging. it may be spiking when you first start to some crazy high overcharge only letting you get 3000 rpms then when you bring it back down and back up it may be only getting up to 16ish volts setting off the horn but not affecting power. Also something else to check if your air compressor is overheating it will sound the horn but not affect power.
 
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