Mercruiser Thunderbolt V Ignition No Longer Available

[pbruley1116]

I have a 2010 Larson 1850LX it came with a Mercruiser 4.3 TKS with Alpha Stern
4.3L V6 with 2 BBL Carb and Thunderbolt V Ignition (Engine s/n 1A612644)

Thunderbolt V Ignition Module p/n 861251-1 is acting up. Sometimes it works and lately most of the time it doesn't. If I do get the boat started it runs good but once it heats up it won't start again.
I have installed brand new:
-Coil and Wires
-Distributor CAP and Rotor
-Ignition Sensor in Distributor
-Spark Plugs

It is definitely a "no spark" issue as I don't get a spark when the engine won't start. I have gone through the Testing flow chart for Thunderbolt V Ignition System and it points to the Ignition Module.

The only thing left to replace is the Thunderbolt V Ignition Module however after contacting Mercruiser I got this response:
"The ICM for your engine was part number 861251T1. It is no longer available and has been replaced with an updated HEI ignition system part number 8M0183359"
The part they are telling me to get is a new distributor kit that costs over a $1000.. You have got to be kidding.
Why would Merc have stopped making a $50 ICM? I feel this is robbery my boat is not that old and further why should I dump $1000 into another Merc part just to have them NLA it and screw me over again.

Is there any aftermarket product that duplicates the the Thunderbolt V Ignition Module?

 

[alldodge]

Being intermittent, not so sure its bad. Electronics dn't work and stop, then start again
If your sure its gone, then I would go to Delco EST

 

[dubs283]

Why would Merc have stopped making a $50 ICM?

Try $750-$900+. And mercury didn't make them. Denso did and whatever their reason is anyone's guess

The upgrade is a gm based hei ignition with the module on the distributor plate. Solid system and from mercury the entire system is priced accordingly.

Don't know of a direct replacement for the thunderbolt module, have never seen an aftermarket one. A lot of people run an msd ignition in place of thunderbolt. Same theory of operation with similar components. Unknown cost of that system tho

 

[Scott Danforth]

Go thru the tests.

Find out if you do have a bad component or a bad connection

The trigger assembly for the dizzy is only $65-70

The amplifier assembly is available only thru MerCruiser

 

[Fun Times]

Could keep an eye on Ebay for both sometimes new and for sure used if desired…, https://www.ebay.com/sch/i.html?_nk...l1311&_odkw=861251-1+Mercruiser+&LH_PrefLoc=2

Kind of rare for this item to fail like this but not impossible…Just a long shot idea is all here but maybe next time the engine acts up of not starting try disconnecting the 2 wire harness connectors at the ICM for a minute or two and see if the engine might restart up normal.