Guage swing & Engine shutdown
 

Hope to find some help from you Z guys! I build street rods and am not that familiar with the Japanese/Bosch injection. I'm trying to sort out a friends 1977 280 . problem, Engine will start and run fine at all rpms untill it gets up to operating temp. then it suddenly dies and will not restart untill it cools down.Fuel pressure is a constant 34 to 38 psi. Injectors are firing as are the plugs. other issue is when ign. is on or car is running the volt meter does'nt work (alt. is putting out 13.8 volts). Also fuel,temp,oil pressure guages swing either when running or with ign. on. Any help would be appreaciated. thanks Al.

The dying problem sounds like a bad ignition control module on the side of the dizzy.

Does it slowly die or is it like you turn off the key? Do you have spark and fuel pressure after it dies?

It just suddenly dies! Checked fuel pressure & spark as well as injector voltage after each episode, every thing is there! Damndest thing I have ever seen! Logic says it should start. I was told that unlike OBD 1&2 the Z computer cannot be scanned. I'm going to check for voltage swing at the guages and try to figure why. Do all guages run thru the computer? Thanks Al.

Some event is shutting down the ecu. Verify this with a noid light. The ecu is turned on by the ignition control module via the ign switch. The dying could be caused by the regulator shutting down after it cycles open. The gauge swing indicates a complete loss of electrical power to the engine harness.
The afm controls the fuel pump so check the tps per the factory service manual. It will shut down the fuel pump if it senses a stopage in air flow.
Please post your findings because this is just one of many problems the newb encounters.