Single click sound when on the throttle

[nsx_overdrive]

Hey everyone,
2001 6spd. I am hearing a single click sound behind my head when on the gas and the pedal is down about 3/4 of the way. Doesn’t seem to matter what RPM I’m in. It is very reproducible. It never made this click sound before. There is no noticeable change in performance. Is this normal? Or do I have a problem? I did recently install a new battery. Is that the issue? I found some posts that it could be related to the fuel pump but I’m not sure. What pressure is normal for fuel pump?

Thanks in advance.

 

[Old Guy]

It might be what Honda calls the fuel pump relay which is actually the fuel pump resistor by-pass relay. The relay is located on the inside firewall just behind the driver's side seat next to the traction control unit, probably between your spine and where your right shoulder is. The relay starts out unenergized and as the engine load increases the relay energizes (which might be click you here) to by-pass the fuel pump resistor and increase the fuel pump speed to insure sufficient fuel delivery.

If you want to confirm that it is the fuel pump relay you could remove the inner bulk head cover to expose the relay which should make it easy to confirm that it is the relay making the click by listening while you drive. Relays normally make a noise when they operate; but, I don't know why you are all of a sudden hearing it unless it is just a matter of becoming aware of it and now you are listening for it. I have never noticed mine.

If you want to replace it, I think it is a Denso 056700-7330. Less than $20 new from Rock Auto.

 

[nsx_overdrive]

Wow thanks for the response I’ll give it a try and report back!

 

[Wild Turkey]

I don't know if this will save you from taking the panel off, but the fuel pump resistor bypass relay is also energised for ~2 seconds when you start the car to pressurise the fuel system. Turn the ignition on without starting it and you will hear the click on and then off in the bulkhead (at least I do on mine) and you may be able to identify if this is the click you're hearing. I also hear the click occasionally while accelerating, @Old Guy's hearing notwithstanding. I think if the injector fuel flow exceeds the pump with it's reduced baseline voltage due to the series resistor, the ECU triggers more fuel pump voltage and pump flow by bypassing the series resistor. Of course the fuel pressure is low when you initially start the car, but I don't know if the relay is triggered by the low pressure or a preprogrammed 2 energized interval during starting.

 

[Old Guy]

It would be reasonable that the ECU energizes the FUEL PUMP RELAY (resistor by-pass) during the fuel pump prime cycle to facilitate faster pressurization of the fuel rail at start up; however, I cannot confirm that. But, it also energizes the fuel pump relay inside the main EFI relay (the relay that controls the fuel pump) at exactly the same time which powers up the fuel pump so you have some potential simultaneous noises if you are attempting to confirm the source of a click at start up. I have never really listened for clicks at start up because it is the fuel pump whine that I want to hear. Whine means good.

I like a good w(h)ine.