90HP 2 Stroke Surging Need Help!

[Mean15]

Hi. I have a 2000 2 stroke 90hp that has been running strong but recently I have been having this surging issue where It wont get over 2500rpm then it will surge on to 4k and plane out then will rev WOT then down to 3k. Its almost like one of the cylinders is going out or a flip is being switched off and on. I have tested the coil packs and they all tested well as well as new fuel. The fuel line from the tank to the motor is free of delamination. Im stuck and cant figure this out help!

[robinr011]

Hello mean,
just so I can get a better understanding.... When you say rev's up to WOT do you mean boat accelerates OR just the motor rev's faster?

Thanks
robinr01

[Mean15]

The boat accelerates, it feels like i'm dropping a cylinder at random rpms

[rickdb1]

Unless you tested the coil packs under a load, it is likely one is bad. ohming them out means nothing. Pull the plugs after it has the problem and see if one is wetter than the others. Speaking of plugs, when was the last time they were changed?

[EuropeanAM]

Before you get too deep into this- try a FRESH SET of the CORRECT Spark Plugs (based on the engine's SERIAL NUMBER).

Cannot stress this enough... I've had two local "techs" spend weeks chasing a similar condition for what turned out to simply be a "Bad Spark Plug".

[Mean15]

I pulled them and even replaced one. They were replaced not to long ago. Should I just buy a new coil pack?

[JOE54]

I wouldn't just buy one without verifying its bad , might be just bad coil as in one

[Mean15]

I'm thinking of taking it out and unplugging one coil pack and seeing if it surges. I'm hoping it will run on 2 cylinders

[JOE54]

timming light will help ya also