Starting starts and runs works well, until shut off, then will not start at all for approx. 3 hrs? is there a heat sensor?

failed ignition lock cylinder needs replaced

replace the flame sensor

It is more likely the board on the LX.
If you have a volt meter check the IND connection on the Fenwal for 24volts while running and keep your meter on it until it shuts down. If the power is still present at the IND while shutting down then it would appear to be a Fenwal problem. It sounds like the temp circuit on the board or the temp sensor it self is bad. Try dipping the temp sensor in a glass of water with a confirmed temp to see if it is accurate.

1975?? it has a carb and points ,check the points gap first if that doesnt work then its carb strip and clean

I'm having the same issue....also sometimes it will run all night...can anyone answer this post

timing has to be off , this car is nothing but problems get rid of it and get a honda or toyota

You need to reset the lamp hours. Here is the manual to tell you how to reset.

http://www.projectorcentral.com/pdf/projector_manual_2606.pdf

Good Luck and please Rate. FixYa!

I am going to assume that it will not run even if you push on the accelerator pedal?
Can you install or attach an old timing light to the spark plug wires, turn it one and try to start it. The light should flash with the engine running, but if it shuts off at time of engine die, and the engine is still spinning, you are losing spark, My suggestion is the cranks shaft sensor on bell housing.
Second, install a pressure gage on the test port on the fuel rail and watch it as you start the engine, fuel pressure should not drop as the engine dies, if it does, the pump is not working correctly. There are two modes of power to that pump, one to start and timed, for only a few seconds to prime the system, and one to run continuously. Find the wires going to the pump at the tank. Connect test light to those wires and watch what happens during crank and at stall, You should not have the pump shut off and the engine dies.
If you have spark, and fuel pump working, when did you last change the filter,,but I put that LAST.
It has to be one or the other of these.
Good Luck

The sensor for the thermostat is probably going bad or has bad connections. It is (or thinks it is) heating up fast and therefore shuts of the heater.