very weak spark

Also, you CAN NOT evaluate spark when cranking the engine by jumpering the start relay.. This does not provide "full voltage" to the ignition.

You must do one of two things:

1--Test while cranking the engine using the key

2--Clip power directly to the coil + from the battery. However, this does not test the "full circuit" and if you leave this clipped on for long you can burn up the points if they "land" closed.

Don't forget could be a bad coil hi tension wire.