I tried searching the forum with no luck. I have a 2002 Honda Accord V6 that is a hard start if it has not run for a few hours. I have recently changed the spark plugs, coil packs, both O2 sensors, and injectors. I suspect some kind of check valve in the fuel line that is not holding pressure so that it starts right up. Does anyone know if there is a fuel line check valve? If so maybe a part number. Or do I just need to replace the fuel pump?
Thanks.

 

I think the check-valve is built into the fuel pump. But don't run out to replace it just yet... You've already thrown a bunch of parts at it.

Don't start the engine by spinning the key directly to START. Try this for awhile to see what happens...

Turn the key to RUN. The fuel pump will run for about 2 seconds. Then it'll stop about the same time as the check-engine light turns off (after it's bulb-check). Then start the engine.

Even if you pause the key at RUN for less than 2 seconds, before starting, that'll pressurize the fuel lines. IF that makes it start every time, then it seems like the lines are depressurizing. BUT it might be leaking back through the pump, or leaking forwards through the FPR. Or even leaking through a corroded fuel pipe under the car.

If it DOESN'T start reliably by pausing the key, then you need to think of other things besides the fuel lines depressurizing.

 

Those are all good points, I still think it is the check valve in the fuel pump. I have tried cycling the key a couple times and then start and it will start right up, I don't see any fuel leaking. I checked the FPR by unplugging the vacuum line to see if fuel comes out of the vacuum port indicating the diaphragm is perforated. So I went ahead and purchased a fuel pump we will see if that fixes it. I sold the car and committed to installing the fuel pump for the buyer, so hopefully that does it.