'85 Mercury Black Max (Video Included)

[cssulliv]

I have a 1985 Mercury Black Max XR2. It starts up great and seems to idle fine but whenever the motor gets up to about 2000 rpm it starts to act strange.

Here is a link to a video of my engine idling, http://www.youtube.com/watch?v=rqi_l3ZpYZI

When you watch the video, about 1/2 way through you will see what I am talking about...that's not me working the throttle, that's the motor hesitating.

Towards the end of the video I do throttle it up to about 3500 rpm so you can hear what it does.

On the water the boat doesn't want to get up on plane and the hesitation issue is still present.

I have;

-cleaned and rebuilt the carbs

-changed the spark plugs

-removed the "black boxes"

Just wondering what else you think I might try to resolve this. Thanks in advance!!

 

[CharlieB]

Re: '85 Mercury Black Max (Video Included)

I'd bet that you have weak/low voltage on on side of the high speed windings from the stator, limiting spark output under RPM and load.

Verify this before spending any money on a $$$$ Stator by downloading the free Ignition Troubleshooting Guide found thru the link at

www.rapair.com

You will need a DVA Meter to do the tests, but it is a very good tool to have cause someday you or a friend will need it again. If you have a decent Ohms meter you may be able to order or build a DVA Adaptor to use with your meter.

 

[cannonford57]

Re: '85 Mercury Black Max (Video Included)

i think charlieb is right. high side comes in around 1800 to 2000 rpms.a timing light will tell ya volumes.connect it to each plugwire and do whay ya just did...fire will drop out on at least 2 of your cyls.

 

[86RajunCajun]

Re: '85 Mercury Black Max (Video Included)

Yep, stator or switch boxes is my guess. Cyls dropping.

 

[cssulliv]

Re: '85 Mercury Black Max (Video Included)

Ok, just tested the stator and everything checked out. However, the trigger readings were bad. Could this be the cause?

 

[j_martin]

Re: '85 Mercury Black Max (Video Included)

Yes