2000 f100.. sprark problems.. wierd one

[mercurypro]

i got a 2000 FOUR STROKE . 100 hp. .. at aprox 2400 rps it begins to loose spark on number 2 and then around 3500 it looses complete spark on number 4 .knowing that this comes froma comon coil i decided to just swap coils around and it did the same excazt thing .. on the same cylinders.. well is it a pulser coil (aka trigger) or cdi?..how can i check this with out buying both or bringing it in.. ( carbs are perfect) plugs are new. thanks... ken...a newbie here:rolleyes:

 

[Vinh]

How about swap coils from 2 and 4 to 1 and 3. If your problem moves to 1 and 3 then it's the coils. If the problem is in 1 and 3 then it's the pulser coil for 2 and 4.