merc 90 hp lost spark in 4 cyls.

[edhow]

I have a mercury 90 hp, straight 6 cylinder which all of a sudden just decided to stop running while i was idling back to my dock. After checking it out i found that i had lost spark in 4 out of 6 cyls. Any help I can get before i start changing parts and wasting money i would appreciate. I believe the engine is a 1988.It has run fine for 4 years.

 

[Merc90HPnewbie]

Re: merc 90 hp lost spark in 4 cyls.

That's odd since most of the parts in the engine are common to two or three cyls. So to lose 4 cylinders you'd have to lose two things at once. The carbs are 1 for 2 cyls, the switchboxes are one per 3 cyls, etc..

 

[edhow]

Re: merc 90 hp lost spark in 4 cyls.

Originally posted by Merc90HPnewbie:<br /> That's odd since most of the parts in the engine are common to two or three cyls. So to lose 4 cylinders you'd have to lose two things at once. The carbs are 1 for 2 cyls, the switchboxes are one per 3 cyls, etc..

How about the trigger, is it possible that that could cause this. I checked the cylinders with an inductive timing light as I have done in the past and only 1 & 3 fire.

 

[Merc90HPnewbie]

Re: merc 90 hp lost spark in 4 cyls.

I'm no expert but I guess it is possible, I don't have the circuit in front of me but I would think four wires would have to fail for this to happen...<br />I will take a look in the book tonight<br /><br />Anyone else with this motor who knows how the trigger is wired feel free to chime in!