My sister in law has a 1990 accord that is shutting off and not starting it seems when it is real hot. it is getting fuel. I thought it was going to be the ignition module but wanted to get some advice first. I have seen other places where it maybe a main relay problem. How can i check the items. all advice is appreciated

The main relay powers the fuel pump and ECU so it could be the problem. It has been reported before. Usually the problem is cold solder joints on the circuit board. It can be repaired/resoldered and is the first place I would start. The other problem could be the IGM and/or coil. and they are more of a substitue and see if it fixes the problem then troubleshooting because it only happens when the engine temperature is high.