Mercury 75hp red band spark issues...

[James_69r]

Hi I recently got a boat with a red band 75hp mercury outboard on the back. Was told it has a slight miss and needed to sort it out. So I've tested it and the miss stopped it revving past 3000rpm when under load. I have done compression test and all were 142-151psi.
have done a spark test and here is what I found. Only cylinder number 1 was sparking so I messed around with the leads and plugs until I checked them all on the good coil and all tested ok then i got spark on 1 and 2. So I thought it was the coils. Pulled coils off and rearranged the order of them to try the dead coils in the good coils position and success those coils sparked so I'm thinking coils leads and plugs are all good...
what's the most likely problem? The stator, trigger or power pack? How do I test the 3 to save me buying parts I dont need.
any tips and tricks?

 

[Chris1956]

Gee, I am confused. When you say red band Mercury, it leads me to think older model. How many coils and cylinders do you have?

Also, not sure any multi-cylinder motor would rev up to 3000 RPM under load, if only one cylinder was sparking.

 

[James_69r]

Sorry for confusing you... I'm unsure of year of engine going by the serial number I think it's an 86 75hp... my friend called it a red band mercury I'm guessing because it has red stripes on the cowling.

It has 4 cylinders and 4 coils

I'm not exactly sure what rpm it was getting up to as the rev counter doesn't work I dont think. It just wasn't reving very much when under load but would rev ok on the muffs.

I did manage to get a spark on 2 cylinders but one was intermittent and from what I've been reading is most likely a dodgy trigger causing the intermittent sparking.

So I need to do resistance checks on the trigger and stator to see if they are faulty and hopefully then I'll know what needs replacing...

i nearly ordered coils but I moved them around and then they would spark so I figure they aren't faulty its b4 the coils causing the issue

 

[Chris1956]

OK, looks to be an ADI ignition. The CDI Electronics web site will have an electrical test for the components.

 

[James_69r]

Yeah I think I've read the cdi website thats pretty much how I got to the conclusion I'm at now... need to test stator and trigger.. I just been trying to find a dva adapter for cheap... but they all around 60-70 I dont want to waste that money for something I'll probably never use again... maybe I can borrow one from someone