One my 90 Civic Sedan with a 1.5L motor I have an occasional starting issue.
What happens is every so often I will go to start the car & it cranks but no start. I will shut it off & try it again & it will start. The first time this happened I thought fuel filter so I replaced it. It did it again & my thought was fuel pump, because I poured some octane booster into the throttle body & it fired right up. So I took it to a shop to have the fuel pressure checked & was told it was 39# & it was suppose to be 50# so I had a pump & screen installed. It has been OK until this morning. It did it again.
Does anyone have ideas as to where I should start checking. As I said this has only happened 3 times in the last two weeks & 2000 miles. It always will start so far.
Thanks,

 

Have you resoldered the main relay yet? It's a common problem. When the main relay is not working, the fuel pump will not prime when you turn the key on but don't try to start. The pump should run for 2 seconds then cut off when you do that. Also during that time the check engine light will come on for the same 2 seconds then go out. If the CEL stays on steady when you turn key on and don't try to start it's very likely the main relay.

39 sounds like the proper fuel pressure when engine is running. It varies according to the manifold vacuum.

 

Thanks for your response. Where is the MAIN RELAY LOCATED?
Also I kind of isolated the problem today. The car was cold. I went out & started it, no problem. I shut it right back off & started it again. On the third try it would crank but not start. After 15-30 seconds It would crank & start right up. So I believe you have me on the right path just not sure what is the main relay & its location.
Thanks Again for your help.

 

It's inside the car, under the dash, bolted to the side of the car directly above the hood release handle. This is a real common repair so there are some good write-ups already on this and other sites if you search for it.

 

Thanks for this info.