# 115 Optimax losing power



## naclh2oDave (Apr 8, 2008)

Well the boat had set up for a while while I was overseas and I finally ran it on Friday. After I charged the battery it started and ran strong all day. I took it out again on Saturday and it was sluggish, had trouble keeping idle without dying but I eventually got away from the ramp. I went through the no wake zone and opened her up but she only topped out at 29mph @ 4000rpm. Normally I get 45mph at 5500rpm but she just wouldn't do it. Since it ran perfect the day before I suspect that the problem is a safety preset by Mercury. I don't know what to check besides the oil which it had plenty. Has anyone had any similar issues with the Optimax?


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## DOUBLE "D" & LV (Oct 2, 2007)

Check for water in the fuel. Could also be you fuel pickup pump or a fouled plug or injector. I would not take it out until it is fixed. If you need someone to look at it, please keep us in mind.


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## Sequoiha (Sep 28, 2007)

Like David, more than likely fuel... These engines are very particular about fuel volume, check your fuel water seperator, and the fuel filter on the engine,,, if you cant take care of it, I can do it for you,,,,:usaflag


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## naclh2oDave (Apr 8, 2008)

Thanks for the help guys, looks like I'll spend the day doing some maintenance. I'll be calling if I can't figure it out.


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## naclh2oDave (Apr 8, 2008)

I went through the system and found no water ingress anywhere. I am going to do a tune up with all filters and spark plugs (had to order them, be in tomorrow) and will let you know how it turns out. Thanks.


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## duckhuntinsailor (Sep 28, 2007)

I would check your fuel before putting your new filter on. Check it by hand pumping some gas into a cake pan (that's what I used but don't let the wife know she got upset), then let it set and look for bubbles forming (water). Also,Optimax hates ethenol,it justdoesn't do right compare your gas to some fresh gas and see if it's colored differently. If you haven't you may want tomix in some fuel treatment (something like seafoam). Lastly you can disconnet the plugs (not the plug wire but the other wire) from coils one at a time to make sure each cylinder is firing if it is not firing there will be NO drop in RPM or audible change in the engine. Good luck, oh and if the fix isn't simple sell it and get a yamaha


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## DOUBLE "D" & LV (Oct 2, 2007)

Fuel quality is what comes to mind first. If you have one, hook up a seperate fuel supply and let it run. If you have a portable tank, then you can take it for a short test run on the water and tet that. You may have to remove the old fuel and refill. How long did it sit and was stabilizer added?


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## Sequoiha (Sep 28, 2007)

NO need to order plugs, we have them in stock...:usaflag


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## naclh2oDave (Apr 8, 2008)

Ok so I did everything I could and I feel that the fuel is not contaminated or old.YesI treated the fuel with STABIL and left it with a full tankwhile it sat up.I tested it for water,there were no signs of moisture and the color is good,then I replaced the water/fuel seperator, the fuel filter and the spark plugs. After all of that it did stop stalling and began to run solidly at idol. So I felt brave and took it for a test drive to see what the RPMs were doing. It ran fine at the ramp but when I opened it up she still wouldn't go above 4000 rpm or 30 mph. Normallly she purrs at 5100 rpm while cruising about 40. Its pretty frustrating but I'm afraid I'll have to take it to a mechanic if I plan on fishing anytime soom.


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## metal11 (Oct 7, 2007)

I would have went with fuel at first but now that you have done all that work I would say you have lost a cylinder or two. I would check for spark on all cylinders and then do a compression check. Get a fuel pressure gage and attach it to the top of the fuel rail and see what you have there also.


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## DOUBLE "D" & LV (Oct 2, 2007)

pm sent.


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## The Maintenance Shoppe (Nov 5, 2007)

MERCURY outboard + long storage = #1 bad fuel pump, #2 dirty carbs.


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## truklodyte (Oct 18, 2008)

After sitting for a while I had carbs rebuilt and had fuel pump rebuilt and added electric back up.


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## naclh2oDave (Apr 8, 2008)

Yep I already had to have one fuel pump replaced, last summer. It is a DFI, so luckily no carbs. I did everything I could on my own and from everyones help I narrowed it down to one of the coils. Since it is a dealer item and the boat is under warranty I took it to a Mercury certified repair shop to have warranty work done. I'd like to thank everyone for the assistance and free advice. Thanks PFF.


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