Originally Posted by barry123400

Clamp off the relief valve return line from the injection pump just in case the relief valve is wide open. Also watch fuel being expelled out the relief valve when cranking for a lot of air.

Best done with a tube into a little bottle with some fluid in it to submerge the end of the tube. This way you can establish if it is fuel or air.

No spillage from the relief valve indicates no or substandard fuel pressure. Lots of air bubbles indicate air ingress somewhere into the injection pump.

Three seconds is also about the amount of time to establish enough vacuum to shut the engine down. Thats if there is a fault in the shutoff circuit. Just pulling the vacuum line from the shutoff device eliminates that as a possibility.It is possible as well as was mentioned in the last post if the vacuum system is pretty good.