1992 honda civic hatchback SI

My car won’t start when the temp reaches around 90 degrees. Will start the first time, but not five minutes later. I learned to push it to shade to start it, or just wait awhile. A mechanic said he remembers that the main relay located under the dash would go on the fritz in hot weather. I am laid off; the part costs around 80.00 dollars. Should I take a chance and replace the relay? Any other possibilities? I can’t afford a mechanic right now but do most repairs myself anyway. thanks for any input. carol

Yes, replace the relay. It’s the most likely cause of your problem.