Sometimes they just go bad. I've replaced quite a few.
They're still cheaper and more reliable than an MSD IMHO.
Gary

From past experiences I would just stay with the stock ingnition system. With that system you have the revlimiter and knock sensor to protect the motor. Switching to MSD you spend more money with more potential problems and is not as dependable.. If there is oil leaking from your coil I would replace that as well.

......I couldn't agree more with the last two posts.

I THOUGHT ON THE 99 HP THE REV LIMITER WAS IN THE OTHER BOX(805443)?? IN FRONT OF THE MODULE

The 805443 is the knock control module( outer),
the 848821t2 ( inner) is the ICM, where the rev. limiter
resides.

here's a pix.

http://www.mercruiserparts.com/Show_...RU+0L001772%29

Ok So If You Unplug The Knock Sensor The Motor Will Run??

Is the Crane box a marine box for $270.00?

Here's my issue - my motors made peak HP @ 5400 on the dyno, so I would like to spin them @ least 5400-5500 - don't really want to drop the coin on MSD (not to mention the reliability factor) here's a question would I have known I was on the limiter or does it retard timming too prevent overreving???

Ran-Dom 32,
I ran my 1998 HP 500's on yhe dyno with the thunder bolt V module and the limiter hit at 5450 rpm and it was very noticable. I have two modules if you are interested, I went with the crane boxes. Jeff

Now I'm even more confused - 5450 ? I thought it was 5350? - how much you want for them? & what benefit was it going to the crane boxes?