mercruiser surging

Ok, so I went out on the lake for the second time of the season and the boat is hesitating at slower speeds (around 16 mph). It only does this when someone is wakeboarding. The engine is an 04 black scorpion 330hp with 27 hours on it. Could it be a gas issue or what do you guys think?

Replace your water seperator and fuel filter if seperate. Always keep your boat full of fuel when not in use, to prevent water from entering. There are many things it could be including the fuel pump, TPS, etc. This is why you have a warranty

Add vacuum leak to the list. Good call on TPS BTW.

Hey thanks guys, good info.

I think I tracked the problem down further, It only surges when perfect pass is engaged and moving the throttle to keep speed. Basically it is like tapping your gas pedal in your car really quickly and lightly. If I am manually pulling a boarder it dosent surge, because I am not constantly adjusting the speed. Also when I am idling out of the dock, just as I give it throttle to go it hesitates. Any ideas?

It is your perfect pass. Why are you going only 16 MPH? Most wakeboarding is done faster than that. If you set it at 19 does it do that? Most people go faster.

Depending on your model, you can adjust the sensitivity of the perfect pass to minimize the surging or adjust it to read the RPM instead of the speed. Your owner's manual will tell you how to do this.

Ah more info. Well also check the tightness of the allen screw on the PP motor. If it is tight play around with the settings and if you still need help Perfect Pass has great customer support.

You may still have a secondary problem due to the hesitation with PP off. Again check the screw.

Thanks guys, yeah I think it is a secondary problem, you can look at the PP cable while it is running and it is working, or so it seems. You'd think if it were PP you could actually see the cable surging in conjunction with the boat surging but it dosen't.
talltigeguy - My wife is pretty small and is just learning to board, so she likes the 16mph speed.

just tow her at 18 and tell her its 16, 18 is the slowest i tow anyone other then very small kids, tell her to "WOMAN UP"

I have a friend that had an 03 Sanger with a 315 MPI Mercruiser with what sounds like a similar problem. His only did it under load and it was intermittent. If I remember right it was an ignition problem and covered under warranty. It may have been the ignition module?? It was an issue Mercruiser was aware of. You might check there.

Give this a whirl. Had a major surging issue at the beginning of the season and thought something was seriously wrong. Checked throttle cable, servo motor, adjusted my settings(kdw nn) and still no go. Not sure what model you have but just do a sytem reset by holdin down menu on/off for %sec and turning the key to on position Solved all my problems was so easy. Forgot all about it.

The pp guys said sometimnes the comp gets messed up when the battery is reconnected at the beginning of the season.

Good luck

Thanks Kris, I'll give it a shot this weekend and let you know how it comes out. By the way, when your boat was surging could you see the throttle cable move in conjuntion with the surging or did it look like the cable was working normal while the boat was still surging? Thanks for the ideas.

Jeremy. What was actually happening w mine IS really really weird. The boat would hold speed and the pp speedo would read find. Thyen once it beeped and the pp engaged the speedo would jump to 42 on the pp hence the engine would cut back and then pp speedo would again change to the lower speed and boat would shoot off like a rocket. Was freaky for sure. What would happen with the surging tho is that the servo motor couldn't keep up so I had a tone of slack in the cable so when i threw in in neutral it would take 15sec or more for the tension to be caught back up tin the servo.


To ansew your question yes or no. It was working normal as all the tests and performance checks and self tightning was right in the money. Was just a computer malfunction, but to me not knowing what the prob was at the time thought ity was paddle wheel prob , but that wasn't prob cuz changed that, and then went to throttle linkage w/ servo motor related but adjusted everything and everything checked out ok. Servo did self tightning and all

Thanks Kris, went out, reset the computer and toned down the KDH or whatever it is, and it is still surging so...I guess back to the shop. At least it's still under warranty.

Jeremy. Call Perfect Pass... they will step you through the trouble shooting. If the problem persists, then they will send the replacement parts and get your to go through the series of steps again until solved. They are great.

This is what I did...

Run in Wakeboard Speed mode... if it surges... visually check the servo motor and ensure it is snug and the cable is tight.

If all looks good... then go into Slalom-RPM mode... if it runs smooth... (which it did for me) then it is not a servo problem.. it is a speed detection problem...

They sent me a new paddlewheel sensor... I have not put it in yet... but it is my next step...

I have just been running in RPM mode because it is ultra smooth towing that way... but you dont get to use all of the features of the new Perfect Pass Software in RPM mode.

I will try the paddlewheel soon.

I had exactlly the same problem and trouble shooting with PP they sent me the paddle wheel. that was not the problem so they sent the computer it has worked fine ever since. Like Kyle said they are great to work with give them a call

Well mt fix only must have worked for 1 time cuz put it in the water and back to same prob. Must have goten lucky for that day. Good thing PP sent me a new module to put in. Did that and Viola fixed once again.


So the reset didn't really work, but as everyone has said. Give em a call they were VERY VERY helpful and they are definitely are a company that still relies on great customer service. TOP NOTCH

Thanks for the info guys. I had a tech at mercruiser call my dealer and they figured that based on the info my engine computer was giving them, I need a whole new computer for the boat. So Wed I should have the new computer and hopefully it clears the problem. I'll give you guys an update next week..

"I think I tracked the problem down further, It only surges when perfect pass is engaged and moving the throttle to keep speed."

So you told Mercury that it only does it when the perfect pass is engaged and they want to replace the Engine computer WOW .......what did perfect passs say when you talked to them???

Kevin, It also does it when I go to give it throttle after idling in gear. In other words the problem is always there but perfect pass makes the problem really noticeable. And actually Mercruiser is replacing the computer based on the computer readouts not really on what I told them. Anyway I just want to get the boat on the water so hopefully they figured out the problem.

Ok that makes more since

Good luck!

So we took the boat to the dealer today and they put in a brand new computer. The new computer completely took care of the surging problem. Apparently Mercruiser has updated the ECM somehow or another. So if anyone has had the same problem as me it could very well be your computer. Anyhow thanks for all the help folks.