NO fire on 2,4,6??

[Leonard Ray]

I have an 1986 mercury 175hp on my boat that has been starting and running great until last week.The boat started good but sound rough.It was very cold so i let it warm for a bit,but never did clear up and would not rev up at all.When I got it home i did a compression test (120 on all cylinders).So i put plugs in it,but did not help. pulled the plug wires off one at a time and there is no fire on 2,4,6 plugs. What do I need to check first? NEED HELP
Thanks

 

[Faztbullet]

Re: NO fire on 2,4,6??

Either a switchbox or stator. Swap the blue/red stator leads and see if problem follows, if so its a stator.If not its a box.

 

[CharlieB]

Re: NO fire on 2,4,6??

2nd test, disconnect the White with black line wire that connects the two switchbox Bias terminals, if spark returns this proves a bad Bias circuit in the box that was always sparking.

Merc recommends replacing BOTH boxes.

Mark the bad Bias box and sell lit to a 3 cyl owner cheap, they don't use the Bias and that box will work fine for them.