Can anyone help with what this is in the blue circle in the picture? When I pulled the wire apart it looks like a fusible link but there was no info on the amp or anything if it is. The service manual doesn't call it out except for this picture which has no description. Any info helps

Looks like it maybe a resistor. See #30.
https://www.mercruiserparts.com/bam/.../30920/2330/40

A resistor woukd make sense so coil doesn’t overheat on a 4cyl. A4cyl has twice the time in between sparks than an 8 cyl, Yes, the module inside controls dwell. But i don’t think the module knows how many cyl’s you have, as some modules sre used for 4 - 8 cyl’s.

Example: thus why back in points years, 8 cyl eould have 1.5 ohm resistor snd 4cyl fiuble that, at 3.0ohm

Thank you. Your image describes this as a "Filter" is this something I can purchase? What do i need to look for to find this "filter"?

Read my post above yours. Lol.

Sorry, just so I'm following. The image calls this a filter, but the link # 30 wire in the next post is a resistor wire. This wire is assembled in a harness (a plug on each end) with this filter in mid ways. Does it make sense that one wire with eyelet ends is the same wire connecting the coil to the distributor The webpage seems to indicate this wire is for that purpose but doesn't highlight the need for a filter. Thanks for the response.

Other people with trouble (and fixed) on 3.0l merc with Est:
NEED 3.0 Mercruiser Ignition HELP!!!!!!

Shop manual for 3.0 eith points, EST, and digital distributorless:

http://panavi.kz/boat/1998/3.0L%20manual.pdf

I see what you are saying. The wiring diagram post #2 shows the ‘filter’ in the 2 wire harness going from distributor to coil. Therefore #19 being this harness, should have one in it.

#19 is

• 84-817376T01 which superceded 84-817376T
  
  also , this harness seems to be the issue the 2 folks in the thread i linked, issues. If, you have sane issue, maybe look into that.