1999 Optimax 150 check engine and horn

fishinfreak27

Recruit
Joined
Jan 14, 2008
Messages
1
I think I have a similar situation as the prev. post with a 200 Opti... This has been an ongoing problem since last August. We have had it into 3 diff. shops now and haven't gotten a solution. So, any and all info is appreciated. The motor will run fine, then all of the sudden the check engine light comes on, and the intermitent beep beep comes on, also, the motor slows to 3,000 rpm. When you stop and put it back into neutral that usually always stops it, then it may go again for another 5 min., or less. Many times when it does this, once you try to go again it won't even let you get back on plane before it goes off on you again, then again. It seems we can go a couple trips with no problems, then it goes off, and it happens several times in one trip. Also, the motor idles higher than it should, 900 rpm, I believe, about half the time. Several people think it may be one of the tps sensors. I have had it at the marina, and they couldn't find anything when they plugged it in to the computer. Just one over-rev. I do have a hot foot, don't know if that has anything to do with it. Replaced the fuel pump, that didn't help. Any ideas guys? Thanks
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: 1999 Optimax 150 check engine and horn

I think these engines are real sensitive to electrical noise. Bad plug wires, poor ground, (anywhere in the engine) or even the wrong spark plugs can drive them nuts.

hope it helps
John
 

TD_Maker

Chief Petty Officer
Joined
Aug 31, 2005
Messages
564
Re: 1999 Optimax 150 check engine and horn

I have a 150 Optimax too. Mine was doing about the same thing, and it turned out to be a overheat in one or both of the cylinder banks which puts the motor in the "safe" mode. Replace the undersized impellar (spelled wrong?)and see what happens.
 

flabum

Chief Petty Officer
Joined
Feb 17, 2007
Messages
567
Re: 1999 Optimax 150 check engine and horn

It's strange that it is tripping the horn and safe mode but not leaving any codes......sounds like a bad ECM
 

Fenwick2

Cadet
Joined
Sep 26, 2007
Messages
26
Re: 1999 Optimax 150 check engine and horn

Best of Luck
 
Last edited:

j442w30

Petty Officer 1st Class
Joined
Jan 9, 2007
Messages
264
Re: 1999 Optimax 150 check engine and horn

What kind of batteries do you have? Optimax engines are very sensitive to battery voltages, you need a battery with a minimum of 1000 MCA or it might cause you some problems. Also check all of the cables and connections while you're at it.
 
Joined
Jun 15, 2007
Messages
8
Re: 1999 Optimax 150 check engine and horn

These symptoms sound very similiar to mine, which is a 99 135 Optimax which is practically the same motor. Shifting to neutral is what cures my issues, at least temporarily as well. After changing all the "easy stuff" I too believe its the throttle position sensors. Did you change yours and did it fix the problem? Is this a DIY job?
 

saltwaterred

Recruit
Joined
Feb 4, 2008
Messages
1
Re: 1999 Optimax 150 check engine and horn

Just a word to the wise, I'm rebuilding my 150 opti (2000 year model OTO67464) because of a check engine and warning horn. The check valves on the block for cyls. 1 &3 vibrated loose
 
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