I didn't mean that gasoline was leaking from the fuel rail. If you lose pressure in the system over time, the gasoline is flowing back to the gas tank. There is a check valve that should prevent fuel from flowing back to the gas tank. That check valve could have failed. Unfortunately, it is part of the fuel pump.

 

Is there any way to test the check valve?

 

You have to measure the pressure in the fuel system and verify the pressure drops when the car sits overnight.

 

The car start fine this morning with the technique you showed me. So, the main issue is the check valve not holding fuel pressure. However, I still not find the port where to connect the fuel pressure gauge to check it.

 

At this point checking the fuel pressure is pretty much moot.

 

It may be that turning the key & pausing for even 1 or 1/2 second at the RUN position will make it start right up. Try & see.

The fuel pressure can leak back to the tank by 2 different paths. The check-valve in the fuel pump can leak back into the tank.

Or the FPR (on the return line) can leak slowly. So the fuel bleeds through the FPR & the return line back to the tank.

Check the vacuum hose on the FPR, shortly after turning it off. You shouldn't have any gasoline in there. Besides running rich, that is another place for the pressure to bleed off, but if that's happening you would have other issues like flooding.

 

Thank you all. With all your help, now I know what cause the issue.
I'll replace the FPR first because it's cheaper and the next thing is fuel pump.

However, if someone know where to check the fuel pressure (1999 Honda accord V6) then share with me.

 

NewHond,

Did you end up figuring out what was the problem? I am having the same symptoms for my 99 v6 Accord too.