While driving the inline fuse 3amp I put inline to protect the ECU megajolt blew and left me stranded.

It has never blown in 7-8 years , why now?

I was told something would have shorted. I mean its just a straight wire from one of fuse board straight to the unit it self.

Are there any tantalum capacitors on your model of megajolt?

Their failure mode is to short circuit, I had one fail on my megasquirt, and it burnt a trace on the pcb rather than blowing the fuse.

The small capacity tantalums look like a fat yellow grain of rice with a lead on each end, big ones like a yellow tictac with both leads on one side, and are polarised so need replacing as removed, this may be marked on the silkscreen and will be marked on the outside with the voltage/temperature ratings.

If you can find the bom for your megajolt, it will make identifying/testing them easier, the failed tantalums will have a very low resistance, and should trigger a meter set on beep continuity test while in circuit.

Dave