Switch box/ power pack mid 80's 90 horse

[McMudpuddle]

Hello all, I am the proud owner of a Merc, 6cyl, 90 horse with an occasional lose of spark to #1. I determined this with the help of an inductive pick up timing light. I switched the wires on the switch boxes upper to lower and the problem moved from #1 to #4. The $150 question is, can this problem be caused by anything other than the switch box?
Thanks to all those who have helped me in the past and with this one!

 

[Barnacle_Bill]

Re: Switch box/ power pack mid 80's 90 horse

That does point to a bad switch box. For further bad news, it is recommended that both be replaced as the new one will most likely be a different revision than the old one.

 

[j_martin]

Re: Switch box/ power pack mid 80's 90 horse

Make sure the eyelet connector on the trigger wire for #1 and #2 is good. If it were loose, it could theoretically conduct only one way. #1 and #2 are opposite ends of the same trigger coil. (it's 1 and 4 on a v6)

On these dual switchbox systems opposite ends of a trigger coil go to 2 different switchboxes, so a fault in the one switchbox could cause the fault that seems to manifest in the other. The bias circuit is also shared between the boxes, and can do the same thing.

Thus, it's wise to replace them in pairs.

hope it helps
John

 

[McMudpuddle]

Re: Switch box/ power pack mid 80's 90 horse

One new switch box $150, A boat that starts on the first crank and runs like a raped ape, priceless!!!
Thanks Guys!