340 ignition problem?

No "what" on the blue? I'm concerned you are not doing the test right Re-read what I posted

Unhook the green wire at the alternator AND LAY IT ASIDE

The thing you are GROUNDING is the terminal on the alternator from which you just got done disconnecting the green wire. You do not ground the wire itself.

You do NOT ground the blue. Check it for battery voltage with the key in "run."

What do you have for a meter / test light, etc?