Cutting out ar WOT

dirty d

Cadet
Joined
Jun 5, 2011
Messages
19
hey fellas. Mercury 1250ss 125 l6 has been cutting out at wide open throttle. I put the timing light to it and was surprised to find that it's picking up spark , and then not picking up anything at all. I timed it to about 37 degrees and couldnt get it to flicker, so I pulled the plugs down the line and no spark.
The cap is old, and the only surgery I did was replaced the rotor and two bearings.Plus polished up the brass on the cap. I'm assuming that the cutting out has to do with the advance spark?
I should also tell you the mercury kill switch has exposed and frayed wire. Obviously not good, but I really dont know when it it supposed to operate and cannot make a ruling on it.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: Cutting out ar WOT

I hope that 37 degrees is a typo! Even 27 is too much, more like 23 with todays fuel.

The tilt switch is to kill the motor if you try to drive the boat upside down, (not recommended). ;) Repair that wire.

Check for old cracked plug wires.

Check fuel pump flow to be sure it can supply enough fuel for WOT.
 

dirty d

Cadet
Joined
Jun 5, 2011
Messages
19
Re: Cutting out ar WOT

Thanks for your response. I have new wires, plugs, and now a new cap. I am now replacing the fuel lines just in case. I rebuilt the carbs and put new diaphrams and gaskets on the pumps, oh, and check valves too.. The carbs, pumps, wires and plugs were all done before I had the WOT problem. In fact, and although the story is long The motor only ran if I squirted fuel directly into the carbs, and this is why I rebuilt the carbs and pumps.
On my distributor cap are three rings of firing orders. The paperwork says to use the inside middle six numbers for 1250 ss, however, it seems to run using the outside six too, which are sequential 1-6 clockwise. Is there something here that I should know? Anyway, this cutting out at WOT problem has me guessing, is it spark or is it fuel? I cant see the spark, but the motor idles good. That leaves me at the coil, but before I replace the coil, would the coil be a cause to the throttle cutting out WOT. PLEASE HELP>
 
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