2000 Optimax 150 hp goes dead in the water

[joecox]

I have a 2000 Mercury 150 hp Saltwater version Optimax that dies when under load.<br /><br />History: The engine has been well maintained, is real clean and has run flawlessly for 100 hours over 4 years. The fuel tank was topped off and stabilized at the end of last season. It is used exclusively in fresh water.<br /><br />Problem: The first time out this year the engine started after 1/2 second of cranking like it always does and ran fine for an hour at verious throttle setting including WOT. After a couple of hours on the water, while accelerating from a stop, the engine died suddenly (as if the ignition were turned off) at approx 2700 rpm. The digital tach showed the rpm dropping rapidly to zero.<br /><br />The boat restarted fine and was able to accelerate to WOT. Over the rest of the day the boat would die about a third of the time I would accelerate. It died more toward the end of the day.<br /><br />I changed the fuel filter and reseated all the spark plug wires before taking the boat out a second time. Same general symptons. Boat ran fine for about an hour and then started dying while accelerating at about 2500 to 3000 rpm. It died once at 4800 rpm. By the end of the day I couldn't get above 3000 rpm. The engine always restarts fine. I've never cranked it for more than a second. I think the engine died once the previous season that I figured was an anomoly.<br /><br />I took it to a certified merc mechanic where the diagnostics testing revealed nothing. He couldn't duplicate the symptons on the water. I am kind of at a loss at what to do next. I have little confidence that the problem solved itself and the dealer is 200 miles away and I want my boat back Do the experts in this forum have any suggestions? <br /><br />Thanks much. ProbWOptimax

 

[jim dozier]

Re: 2000 Optimax 150 hp goes dead in the water

Was it overheating?

 

[Trophyboy]

Re: 2000 Optimax 150 hp goes dead in the water

Hi, Sounds like the same kinda thing that happened to my 2002 135 Opti . First trip out after the yearly annual maintenance rip-off, my motor began doing similar dumb stuff. I took it back three times and they couldn't get it to fail or show anything on their fancy DDT stuff. They were thinking I was nuts when they FINALLY put it on the Dynomometer thing, put it under big load a what do you know it failed! But while it was coughing, sputtering and dying the fancy monitors still showed nothing. They finally reached down and touched the low pressure fuel pump and it was too hot to touch. That was the problem! They wanted $225 plus an hour labor to change it out. After a little resarch, I found the OEM pump online for $99 and changed it myself in ten minutes. Its now fine and running 25 miles off shore chasing Salmon. I would suggest... take it back out and get it to fail again, stop,take the cowling off and feel the pump. It sits on the port side down low and is mounted vertically. Its black, about two inches in diameter and about 5 inches long. Its tie banded to a bracket and has a fuel hose coming out each end. If it ends up being the problem post back and I'll tell you where I got it. Good luck!

 

[joecox]

Re: 2000 Optimax 150 hp goes dead in the water

Nope not overheating and the low pressure fuel pump was only warm to the touch. Was out with the mechanic for 45 minutes yesterday and the darn thing wouldn't fail. He said the problem sounded electrical. I am going to change the battery and run it hard this weekend. Thanks for the suggestions

 

[Trophyboy]

Re: 2000 Optimax 150 hp goes dead in the water

Hi Back, Thats not surprising...like I said in my post, they had a hard time getting mine to fail too. From what I understand from my ordeal, electrical malfunctions affecting the injectors will show as a hard fault on the DDT. The fuel pump issues don't and didn't. I also was told that cool gas is in that pump and it shouldn't be warm never mind hot. I'm still betting on the fuel pump. Let us know what you find.

 

[joecox]

Re: 2000 Optimax 150 hp goes dead in the water

Worked it pretty hard over the weekend and it failed only once. Much better than the previous time it was failing. Obviously not fixed though. When you were having your problem, did your engine die completely and suddenly? Thats what makes me think electrical, it's as if someone turned the key off or activated the safety switch. The fuel pump was no warmer than the rest of the engine, but then the engine wasn't failing either. Thanks again.

 

[2springers26]

Re: 2000 Optimax 150 hp goes dead in the water

opti maxs are battery dependant make sure the batt Is GOOD( cheap batts in optis are not a good idea)... if the cables are loose.. the motor WILL die.. it will fire back up.. take the wing nuts off & use lock nuts.. a ddt will give you a faul history If the problem is elec.. Your tech is still responsible for mechanical... sound like a loose battery to me.. i see it all the time..

 

[joecox]

Re: 2000 Optimax 150 hp goes dead in the water

You may be right. It was a fairly new designer/beer can/expensive battery and the mechanic reported it didn't have a very good charge. I changed the battery and the boat seemed to run much better. There was that one failure though. I had to reem out one of the positive connectors to get it to fit on the battery post. I'll check that connection a little more. Thanks again

 

[joecox]

Re: 2000 Optimax 150 hp goes dead in the water

Final Post:<br /><br />I've run it hard for about a month now and it is running great. Finally got it into the local mechanic who said it ran great for him all day. He did notice the tps (throttle position sensor) was out of adjustment and corrected that. I'm inclined to believe it was the tps first and a weak battery second. Who knows I'll just knock on wood. Thanks for the help

 

[Lizzy K II]

Re: 2000 Optimax 150 hp goes dead in the water

I am having this same problem. My battery has been out and I had it checked. It checked out good and I also installed a larger gauge ground wire. I had an air leak in the fuel system but I fixed that and I am still having this problem when I run the motor under a load at the boat ramp. The high pressure fuel pump is brand new and the low pressure electric pump is one year old. I'm pulling a 4 in. Hg vacuum with the diaphragm lift pump on the motor. I dont know what to do ... please help... The motor runs good for 1 to two minutes and then cuts out and dies. It will idle all day and will start up quickly every time. The only other symptom I have noticed is that on a cold start...the motor will rev. up to 3200 RPM on its own. I turn it off when it does this and try again. Usually the motor will rev up again and then slow down to an idle and run flawlessly until I try to put it under a load...I'm clueless at this point