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Guest lacman

2012 Optimax Pro XS 115 Motor 'Sputter/Hesitation'

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Guest lacman

I have a 2012 Mercury Optimax 115 Pro XS on a Princecraft Expedition 170 which sputters/hesitates during the following times:

· sometimes at slow speeds

· when coming on plane only when I slowly apply the throttle

This is just a momentary hesitation/sputter and then seems to go on running fine. When I punch it on plane there is no hesitation, only happens when I slowly apply the throttle.

Took it to the local dealer and they didn’t even bother to check for any issues. They didn't check plugs, fuel lines, coil, nothing. I don’t even know what to do since they won’t do anything to try and find the problem? All the dealer said was it could be the fogging oil they put in the cylinders last fall. I doubt that since I have ran the boat over 30 hrs since then. I'm pretty frustrated at this point.

Any thoughts as to what this could be?

Thanks

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Pro fisherman-Stud Muffin

not knowing the engine all that well it could be a bazillion things but it does sound like a TPS . easy to test, ohm it out with an analog meter needle should do a smoothe sweep.

have you done plugs? and fuel filter? those are regular maintenance items.

also be sure none of the wire connectors are unplugged.

does it only do it when it warmed up? or cold too?


><^> ........ <^><

 

2016 Dog Lake Open Champion.

Thunder Bay BASSmasters Vice-President 

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Guest

I always warm the motor up before I take off. I was told the Opti's almost never need their plugs changed? Don't know how true that is?

I think I will change the fuel filter and plugs as you have suggested....2 relatively inexpensive things to try first. Kind of annoyed the dealer won't even try and find the problem. I shouldn't have to do this on a motor that has warranty.

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Pro fisherman-Stud Muffin

i have heard plugs easily foul on the opti's during the break in cycle as they consume more oil.


><^> ........ <^><

 

2016 Dog Lake Open Champion.

Thunder Bay BASSmasters Vice-President 

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Adrian

My 2005 Opti 75 (same powerhead as the 115) does the exact same thing, and has since new. Changing the plugs helps for a few hours. I got the same response from a dealer. The issue always goes away after it is fully warmed up. I usually run at 4000 rpm, and it is ok after warmed up. If I run at 3500 rpm, it may take a little longer to go away. To me it feels like a rich fuel mixture. The plugs do come out darker that I would like to see.

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Pro fisherman-Stud Muffin

i know on the bigger opti's they recommend running quickleen in gas to save plugs from fouling and injectors.

you should try a few tanks with quickleen. iof it works just run it more diluted to keep it all good.


><^> ........ <^><

 

2016 Dog Lake Open Champion.

Thunder Bay BASSmasters Vice-President 

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Trevor Zimak

not knowing the engine all that well it could be a bazillion things but it does sound like a TPS . easy to test, ohm it out with an analog meter needle should do a smoothe sweep.

have you done plugs? and fuel filter? those are regular maintenance items.

also be sure none of the wire connectors are unplugged.

does it only do it when it warmed up? or cold too?

This is not a TPS issue. The Throttle Position System controls the rpm's of which your motors idle down upon starting. If you had a TPS issue your idle RPM's would be erratic. Could be as a high a 900-1000 even and then back down to 560 where most Opti's idle. There is definately a fuel issue somewhere. There could be a clog or crud somewhere in the fuel line and the motor is unable to get the appropriate amount of fuel until fuel pressure is increased upon throttling up. Or their is a possibility there is a crack in the line somewhere (doubtful) because you should smell gas. If you have no lose of RPM's or speed at WOT then there is no issue with your coils either.

I would get a dealer to check all fuel related concerns and pressure test as well. Other possible diagnosis could be bad or stale gas (run queekleen as mentioned) Another slim possibility is that you may have a torn or ripped Tracker Diaphram Value which is located on the Port (i think that is the side) side fuel rail (round rubber diaphram).

Lastly, I dont know what the hours are on the motor, but cleaning your plugs could be a cheaper fix, as the Opti run a rich mixture of oil during break in and are recommended to be changed after ever 100hrs.

Good Luck

- Zimmers

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Squaretail

The tps actually relays info to the ECM all the time not just idle. So always a possible candidate. But in reality with an opti sensor failure is rare but does happen. Opti's are not supposed to have any hesitations throughout the rpm range If running in the water. On the hose they do fart and pop erratically with the absence of exhaust back pressure. The most common isssue is debris in the thermostat or blow off valve causing motor to run cold but if the ECM sees the motor is running to cold it will log a code and turn the horn on. Basic rule of thumb is if you have warranty which a 2012 would don't touch it. If you think you know what your doing still don't touch it. If your not confident with the dealer try another, you payed for a new motor for a reason have it fixed properly and in timely manner.

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