Hi guys

A friend of mine has a 1994 civic (automatic transmission), when he comes to switch on his engine after a short period of time after atrip (even short trip), the engine won't start.
But finally it starts after many attempts, what might be the cause?

 

Can you describe in more detail how it's not starting? Is it cranking and not firing? Is it just clicking without the starter engaging?

 

As mentioned, more details about the problem are needed. If the starter cranks the engine fine but the engine won't start, then listen for the fuel pump priming and check for spark and CEL codes.

 

You can re-solder the main relay circuit board solder joints for basically 'free'. those things tend to be a bit problematic. The solder joints tend to crack (use a magnifying glass to inspect them).

 

^The main relay is a likely culprit but it's a better idea to troubleshoot to first identify it as the problem.

 

Thank you my friends for your response.
The starter cranks the engine and the spark plugs are new but the engine does not run.
The fuel pump priming is heard when you turn the key on and the check engine light goes off, every thing seems good.

 

You need to check for bright white spark at the spark plugs. Click Spark link in my signature.

Also inspect the distributor cap and rotor. How old are the plug wires?