Clutch Mystery

[ccstelmo]

Buckle up and put on your thinking caps. This is tooooo weird!

My truck is a 1968 GMC cab and vin on a 1972 3/4 ton FWD frame, stick shift.

The motor was recently replaced with a 1999 350 Vortex by a very competent guy who has probably done 1000 R&R's over the years.

Starting Sequence:

1. Put the tranny in neutral
2. Turn the key, engine starts and runs smoothly.
3. Depress the clutch Pedal.
4. Engine dies.

There is no neutral safety switch on this vehicle. I have looked for vulnerable loose wires that could be pinched by the pedal and linkage and have found none. The engine does not seem to be "loading" it just dies.

Other symptoms:

If I put rearward pressure on the stick and depress the clutch pedal half way, the tranny slides into gear. If I then continue to depress the clutch pedal fully, the engine dies. In other words, depressing the pedal ALL the way triggers the engine to die.

Comment:

This feels and sounds like an electrical issue but as I said, I've searched for loose wires and found none.

Any ideas for me?

ccstelmo