Major help needed.. Mercruiser 140 hp 1986

[biggjimm]

Check the coil like flipbro said. You may have to get a hold of the tech dept at flamethrower though as I found out different coils have different specs. I had a coil that tested "bad" as per the generally accepted guidelines however, upon contacting the manufacturer, it was actually just fine. Jim.

 

[Motodox]

Thank you everyone for the advice and direction on tracking this problem. I have like 7.9 v at the coil with the key on. I have around 3.2 ohms between the post on the coil. I will check resistance on the coil wire after work.

Maybe I should call flame thrower and double check what they call for.

What's weird is I can have my volt meter out one end in the + post on coil and ground to the engine I have 12v. I can also have the black wire off the - post of coil which runs to the ignition module under cap and get 12v but soon as I bring that wire and my test lead to the - post of coil it drops back down to like 8v ... Is this because the coil is sucking up the power? Is that ignition module actually grounded cause I don't understand why I'm getting a good ground from the black wire coming out , idk maybe that right. Is that where the coil gets its ground? I have two wires coming from - post on coil one great which gots to shift interrupt and one black that goes to ignition control module.

I want to pull my hair out !!

How big of a gap should that spark jump to tell if it's sufficient, I have a spark plug tester with a adjustable gap

 

[biggjimm]

The module grounds the coil - terminal which causes it to spark. When testing the resistance of the coil, remove all the wires from it. I think there's something in the stickies that tells you which setting to have your ohm meter set to. I don't recall but it's a different setting for each test. You want to check both the primary & secondary sides. Pos coil term to neg coil term & then move the black lead from the neg term to the center & measure resistance from the pos term to the center tower.

Temporarily unhook the wires going to your shift interrupt & the tachometer, only have the wires going to the distributor on the coil - & the wires from the ignition switch to the coil + & see what it does. Try jumpering directly from the battery + to the coil + & see what it does with full voltage to the coil +.

I think it should jump at least a 3/8" gap. I can't remember & I'm not home to look at my tester.

 

[Motodox]

The module grounds the coil - terminal which causes it to spark. When testing the resistance of the coil, remove all the wires from it. I think there's something in the stickies that tells you which setting to have your ohm meter set to. I don't recall but it's a different setting for each test. You want to check both the primary & secondary sides. Pos coil term to neg coil term & then move the black lead from the neg term to the center & measure resistance from the pos term to the center tower.

Temporarily unhook the wires going to your shift interrupt & the tachometer, only have the wires going to the distributor on the coil - & the wires from the ignition switch to the coil + & see what it does. Try jumpering directly from the battery + to the coil + & see what it does with full voltage to the coil +.

I think it should jump at least a 3/8" gap. I can't remember & I'm not home to look at my tester.

Ok thanks man, really appreciate all this. I'm going to try all this when I get off work today. I'll be back with what happens.

I know I have tried connecting battery jumper straight to + on coil and didn't get much.

All I know is this is driving me crazy, I wish I could find out if my module was bad or the coil. I'll be back with more details after work

 

[Motodox]

We are still working on this problem if you have any info or would like to help please go to the new thread or topic. I created a new topic to help clarify my problem and my trouble shooting performed.
Here's the link.
http://forums.iboats.com/forum/engi...tarting-issues-troubleshooting-performed-lost