Nick,
#1 As others pointed out, your starter bypass wire to the coil is missing. If you've got a points style ignition you have power to the coil running through a ballast resistor or resistor wire (usually tinned). It's only about 6 Volts at the coil. A bypass wire from the starter solenoid (yellow/red I think) supplies a full 12V when cranking. This should be connected to one of the small screw post on the starter solenoid to the + side of the coil. There should be a large red (+ battery), small yellow (ignition crank/start) and yellow/red? (bypass) on the starter.
If you've got a newer Thunderbolt IV with an older wire harness. You can skip the ballast resistor and just run 12V to the coil with the ignition on. Tap into the purple wire from the ignition.
#2 is a short. Which fuse is blowing? The one on the red wire side of the ignition I'm assuming or is it the main breaker? What else is on that fuse. Try turning EVERYTHING else off, then try cranking. Does it still blow? Is the fuse the right size?
Gary
Gary

Remember way back in school in science class where you had to plug a light bulb into a battery to learn the concept of how an electrical arc causes light in vacuum.

My battery was dead... and it still is.

I dont know **** about electrical. I dont have a meter, and I dont know how to read one. The frickin wire cage under my steering wheel looks like a rats nest to me... soooo many wires.

Im in over my head on this one... I dont know what the hell Im doing.

Ill try to figure it out this weekend.

Im printing this out now, and taking it with me, along with a flame thrower, sledge hammer, and other "electrical" tools...

:mad: :mad: :mad: :mad: :mad:

Nick,
I use the "Bigger Hammer" approach when it comes to computer problems. It seems you have the same attitude when it comes to firearms. Maybe that will work on the boat too. BTW, all you should need is a Voltmeter and wire cutter/stripper. Time to go to Radio Shack. Maybe you can get a bigger hammer there too.
Gary

Yo Nick, didn't the wifey say you could buy a new boat? :D

And then I woke up...

:eek: :eek: :mad: :mad: :D :D

Nobody responded to this. I am experiencing this anomally (sp) myself. The ignition has a key that powers up, then a rocker switch to start. After pressing the rocker switch, you can let go and the starter continues to crank, even if you turn off the key. When engine starts, the starter quits. I am thinking a sticking solenoid but seems it would stay stuck after the engine started. Any ideas?

PROBLEM SOLVED!!!!! TRADE BOAT FOR A NEW ONE!!!!!!!!!!!!!! :D :D

Im not rich!

I have a 30ft SCARAB with TWIN 502's that does mid 70's.

I paid 25,000 for it.

It looks great, and runs good in every way except little bull**** like this.

Ive never had a severe or even moderate engine or drive failure.

Im doing ok.

:mad: :eek: :D

And by the way, the only way to have a boat with NO PROBLEMS of ANY KIND, is to

NOOOOOOOOT HAVE A BOOOOOOOOAT.

:mad: :mad: :mad: :mad:

Nick, go to any marine parts supplier west marine boaters world ect... purchase a seloc or chiltons mercruser manual ..they have all basic wiring schematics with easy to understand line drawings, simple to follow . AS a matter of fact I have one that covers your year.. e-mail me and you can have it its an extra (US oso Scarab guys stick togeather) Dave..E=MAIL= [email protected]