Mercruiser Coil Wiring

[Lloyd R]

I was boating and my 1996 Crownline 7.4 Mercruiser stalled. I tried starting and noticed spark at the top of the coil. I was coming out the side of the tower. It looks like the previous owner put an automotive coil on.

So, not being a electical mechanic, I began trying to figure out what electrical system I have. Thunderbolt IV or V. I'm still not 100% sure.

Also, I noticed their is a resistor block and some splicing of a wire that goes to the block (yellow wire) and the other (red wire) to the starter.

Since this seems very dangerous as it is, I would like to return it to factory wiring set up.

Any suggestion?

 

[Scott Danforth]

If it's a resistor block, the thunderbolt ignition has been changed

Post a picture of the distributor without the cap

A ballast resistor is common with the Mallory/Sierra YLM distributors, along with a few orhers

 

[Lloyd R]

Thanks for taking an interest in helping me out!
This is with out the cap.

 

[Lloyd R]

Here is the back side of the distributor.

 

[alldodge]

You have a TBV ignition and the prior owner is a dumb A$$

Remove the resistor mounted on the boat

Get the correct coil, inspect your wires as they may need replacing, than go boating

 

[Lloyd R]

Ohh man your awesome. I agree with your assessment of the previous owner. You should have seen the nightmare starter situation I had to fix last year.

I want to fix the wiring. In pic #3 labeled "Spliced Wires", the "red" wire with a butt connector has a splice with 2 leads. Red to the starter and yellow to resistor that I'm doing away with.

On the coil I had 2 grey to - terminal. On the + I will have one purple and one Blue (goes to oil pressure switch).

Is that all good?

 

[alldodge]

Do some really good tracing because from here things are not correct.

My pic for a standard TBV has 2 gray on the Neg, and one purple on the Pos. The Yel and Blue should not be there.

Having a Blue on the Pos side of the coil would lead me to believe a different oil pressure switch has been installed for some reason

I'll ask, does this motor have a mechanical fuel pump or electrical?

Next
What is the serial number of the motor? It should be found on the flame arrestor or on a plate just above the starter

 

[Lloyd R]

Wow, this makes me pause. I really want to get it back to original.
I will have to get that serial number. Hopefully tomorrow afternoon.
Thanks for your help