Got a 1994 Delsol VTEC b16a3, fuel pump only primes half-time, and once it primes car runs perfectly.
I also notice that When my key is on position II the engine light will keep on but once the light is off
the pump prime and engine can start.
I have replaced ：
fuel pump
map sensor
fuel filter
fuel injector

However, What I placed may not really point to the issue. Someone told me it may be the ECU was faulty or something.
Got this issue for a week already.
Before that My car was fine and everything was okay, it just happened suddenly last week.

If anyone has any ideas please help. I will really appreciate it.

 

This is what broken means... before it was fine, now it is not. You have been throwing parts at it and you are frustrated.... I get it. Your problem is the ECU. When components inside it start going bad, you get the effect that you have described. Replacing capacitors may fix your issue, but the longer you wait to upgrade the caps, the greater chance that other components inside the ECU may be damaged making the ECU a lost cause. You can test this by substituting a known good ECU with the one that you have now... it doesn't have to be a P30 like you have now just to crank the car and idle it... but this will show the difference in overall behavior.

Get testing.

 

I second this diagnosis.

And also add that IC17 is most likely the culprit, aka TA8903SN available on eBay and requires soldering. Capacitors should be changed out with ones of the same values as well.

 

it's a good idea to have a spare ECU anyway just in case.... but before I changed the ECU I'd replace that fuel pump again and check the rubber line coming out of it. I had one burst and it created a problem where it would get progressively worse until it just wouldn't start because the hole kept growing. I've also bought new fuel pumps and they were faulty. do the mechanical crap first because it's generally the moving parts that fail first.