My 1991 honda civic

sometime when i turn the ignition key the engin turns but it wont start ,i leave it alone for a few minutes and try it and it will start right away,help me please, thanks.

Replace your main relay, when they start to fail they exhibit the exact symptoms you describe.

Thank you!
shiraz54

Fuel pump. Same problem.

Yes, the fuel pump can cause the same symptoms if it dies. But on those early 90’s Hondas, the main relay was notorious for dying, and it’s a very cheap part to buy and a very easy part to install (and actually if you’re halfway decent with a soldering iron it’s very easy to fix) so the smart money is to do the MR before you go to the time and trouble of ripping out the back seat to get to the fuel pump.

Another situation is drainback of fuel to the tank, reducing fuel quantity and pressure at the engine. That’d show itself when the car has been sitting overnight or longer. Turning the key to Run/Off/Run/Off a few times and then all the way to Start should get it to start right up if that is the underlying cause.