Rev 318 in park, slows down and stalls..case study.

Here is an update after spending most of a day going through process of elimination stuff.

1. I did pinch the fuel return at the filter and there was no change.

2. I removed the gas cap. No change.

3. I removed the fuel pump inlet line at the frame rail and used my electric pump to pull fuel from the tank. It produced an ample volume of fresh, clean fuel.

4. I then plumbed in a cheap, clear plastic filter between the pump and the carb so I could observe whether the line is emptying during this sudden stall event. It is not. The filter remained full of gas at all times.

5. Finally, I revved the engine fairly hard, made it quit again and then pulled the top off the carb. Float bowl was full to the top.

To add a couple details....when you drive, the engine tries to die suddenly, but if you back out of it quickly and feather the gas it will recover and you can "drive out of it". It will not nose over afterward until you return to closed throttle and accelerate again.

The Electronic spark control is totally out of the picture. '79 vacuum distributor feeding an HEI module mounted on a heat sink, powered through a relay and controlling a TFI coil. The EGR is offline.

The main reason I've went through this diagnostic effort and didn't just start with the carb was to rule out assumptions and "must be's" and find the PROBLEM without throwing parts. It's a tough one. Hope you find this interesting.