Optimax pro xs 115 hesitation

[Nitroz6]

I have a 2013 pro xs 115 hp outboard. There is what seems to be a misfire between around 1500-2000 rpms. Anywhere in this rpm range the outboard surges slightly (revs up and down). When it gets over 2000 rpms, it immediately clears up and runs perfectly. It starts up and idles perfectly. I have tried replacing the plugs twice which are the correct plugs and properly gapped. I have also swapped all three coils and wires with known good ones, all with no change whatsoever. My next guess would be dirty injectors. I have pulled apart the vst and it was completely spotless. It has a new battery rated at 1000 mca. I’ve tried searching forums with no luck. Has anyone ran into this before? Thanks in advance.

[06 SB]

What prop and have you played with the PVS plugs in the prop? Any alarm beeps during the hesitation?

[Nitroz6]

It has the stock laser2 22p prop. It has two large hole plugs and one removed. That is the hot setup for my 2013 nitro z6. If you go straight to wot upon takeoff, there is no hesitation. It revs right up and planes out with no issue. There is no alarm at any point. There is only an issue between 1500-2000 rpms. The motor itself starts shaking pretty bad and you can feel it shaking the whole boat. It accelerates just fine and tops out right at 50-52 mph on gps at 5800 rpms.

[EuropeanAM]

That RPM range isn't particularly smooth... very little effort was put into it, as most boats won't run in that range (without just pushing water at high-load).

Make sure the engine is coming up to temp properly- if it is not, that can cause problems.

Side note: Be sure to provide your Serial Number when posting. Thanks!

[Nitroz6]

I have had several boats and haven’t seen one run as rough as this. It is my first Optimax, perhaps it’s jist the nature of the beast. The serial number is 1B976733. I have a friend who has the same outboard but it’s on an aluminum tracker 175 walk thru deep v and he says his doesn’t vibrate at any speed or throttle position. I haven’t personally been on the boat. It seems abnormal to me but like I said, it’s my first Optimax and I feel like the motor would be under more of a load on my boat than his. So it doesn’t seem like a symptom of dirty injectors? I’ve tried going through everything I could do myself.

[EuropeanAM]

Might have your dealer go through SB 2013-11 (which is still outstanding on your engine serial number). I wouldn't spend any more time on this AT ALL until that has been done, as there is a potential that the items covered in that bulletin are the problem.

[TritonTRXV8]

Like Don said that rpm range on the 1.5l optis isnt really tbe smoothest. Mine never has been either been that way since new. It doesnt vibrate or anything just doesnt sound quite the same. As long as its not shaking or stumbling i wouldnt worry too much myself.

[Nitroz6]

Thank you guys for your input. I made an appointment to have the service bulletin done. I will post the results. Thanks again for your time.

[TritonTRXV8]

Let us know if you find out anymore.

[Nitroz6]

I finally had a chance to get the outboard in the shop. Apparently Mercury sent four notices to the original owner telling him to bring the motor in for the service bulletin which he didn’t do and now they refuse to pay for the repair. The dealer told me I’m looking at 4 hours labor just to check it out. I think it’s pretty horrible that Mercury won’t take care of a problem that they caused. I am going to pick it up and check the reeds myself. Thank you Don and everyone else for your help and thanks for nothing Mercury and the original owner.

[EuropeanAM]

You can thank the previous owner on that, but don't think you can really disparage the manufacturer since both the Factory Warranty AND any Product Protection period ended last year.

You shouldn't have to pay 4 hours to CHECK them, though. That's pretty high...

[Nova Kaw 650]

Have Don send you out a new set of good reeds, and just change them.

[Nitroz6]

It seemed high. If I want to check the reeds myself, I need to remove the lower cowl, oil tank, and air plenum cover. Is that correct?

[Nitroz6]

It seemed high. If I want to check the reeds myself, I need to remove the lower cowl, oil tank, and air plenum cover. Is that correct?

[JOE54]

yes , and a factory ser manual would also help you out

[SilverFox579]

yes , and a factory ser manual would also help you out

+1.

I wouldn't attempt reed replacement without a factory service manual.

[aarchdale]

I put Chris Carson reeds in mine. It is pretty straight forward, just a little time consuming.. My Motor also has a little hesitation at those rpm ranges. Idles fine and WOT is smooth

[EuropeanAM]

Some of that may be related to your flash, Andy (depending on what items you changed when you "flashed" your 75hp). Can't just change the donut and flash- there are other differences.

[aarchdale]

The hesitation on mine is so minor that ive never worried about it. I understand there are differences in the 75 and the actual 115. But the flashed 75 runs great. Had mine done for over 3 years now. Motor has over 1000 hours on it and never lets me down.