2002 Mercury XR6 150, issues below 3300 RPM

[dltigers3]

Hello, I have a new to me 2002 mercury XR6 150 on a Procraft 180 combo. I got it at the beginning of the summer and it seemed to run fine. This past weekend was the first time I had more than 2 people on the boat. When I went to take off, it took a while to plane out, and the engine was making a womp noise over and over. It clearly was not operating at full power. Once on plane and above about 3300 RPM it had full power and sounded smooth.

I went out today and tried a new prop with less pitch to see if that helped, and it did not. With just me in the boat it isn't that noticeable because it gets on plane and above 3300 RPM much faster. I took my grandpa for a ride and he notice that when it is making the noise and struggling, the motor is shaking from front to back. Once on plane the shake is gone. I took some videos of it and posted them to youtube. It is kinda hard to see and hear what it is doing, but if you watch them you might get the idea. Here is the link.

https://www.youtube.com/playlist?list=PLIEd8SHUYnvqMuzCRVRuLXzQugQ2U7Hov

Any help would be greatly appreciated, my wife never wanted the boat in the first place, so now that it isnt working right I'm really in the dog house... haha

 

[dltigers3]

anybody with any ideas?

 

[Dukedog]

Wish I could help but its an "'lectronic motor" and can't make heads nor tails outta tha videos. Really needs ta be dva/computer diagnosed.....jmo

 

[dltigers3]

No Title

Thanks for the response. I did find some disconnected wires that i marked in the picture. Couldnt trace them back to figure out where they come from.

 

[dltigers3]

No Title

 

[Dukedog]

Looks like tha "exposed male" bullet plug is for a temp gauge. Can't reall tell tha color. Should go to tha one in your hand if its coming outta tha harness. Useless if you have no temp gauge. Tha one next to tha bullet, if purple, is a key switched "12v hot" not being used. Tha gray not being used is an extra tach feed.

Here is OEM manual. Be patient. Takes a while ta load.....

.http://boatinfo.no/lib/mercury/manuals/135-150-175-200.html#/172

 

[dltigers3]

Thanks for the manual. I was hoping that one of these wires might be the problem, but I guess not. Anyone with any ideas on my problem? Its just weird to me that it only happens below 3300 rpm, after that it is fine. But if I drop back down it starts messing up againbeven if im still on plane, until I get back above 3300

 

[Dukedog]

Just a guess 'cause I haven't jacked with tha 'lectronic motors much but thinkin' tha WMV's have idle, mid and main circuits I think. Might be somethin' you might take a look at. Might be something in tha manual 'bout it.........

 

[dltigers3]

So i posted about my issue on another forum, and have had a couple people say to check the fuel lines/filter/pump, and anti siphon valve. Would a restriction in fuel cause my issues below 3300 rpm and then work fine above that? It just seems to me that a fuel restriction would get worse the higher you run.

 

[Faztbullet]

More like a carb possibly floodimg....

 

[Dukedog]

More like a carb possibly floodimg....

Agreed.....A "fuel restriction" that most refer to will usually get worse with rpm increase...but always a good idea ta check those things mentioned as a normal maintenance thing.......jmo

 

[Chris1956]

You might check the fuel pump diaghram for leakage. At low speed, a small leak will foul a cylinder lowering the power. At higher speed, the fouling will not happen.

 

[dltigers3]

next week I'm going to do new fuel lines/bulb, filter, and rebuild the fuel pump. Also going to go ahead and put on new plugs and see what happens. if anybody else can think of any other possible cheap fixes before i get into the powerpack/stator please let me know.