Thread: Whining from fuel pump

Very interesting comment Grumndriva,.........Because each & every time I remove the fuel cap to fill up, there is always air sucked into the tank as if there is a vacume within. I'm going to loosen the cap tomorrow & see what, (if anything) happens?
Thanks for that thought, I'll keep you posted,.............

The cap is supposed to do that as the venting is via the charcoal canister in the engine bay .
This is controlled by the computer to vent into the plenum while the car is moving and on light throttle, via the solonoid operated valve on top of the canister.
The tank can either have a vacuum or pressure depending on temperature, but usually has pressure after a long run from the increase in fuel temp because of the fuel circulation through the fuel rail.
Regards Philip A

Have you tried bleeding the fuel system?

With my D2a I turn on ignition and press accelerator 7 times to the floor.....then it runs through its routines. I do this after every fuel filter change.

....ahhh but mine is Td5...

Hi PhilipA,

Good explanation, although mine (V8) has never had positive pressure: always a lower pressure than ambient.

My point for what it is worth was that my vehicle did not make the noise when the tank was unintentionally vented via the leak in the system breather, but apart from that it has made the noise as long as I have had the car (110,000km). Consequently I don't believe that (at least in my case) it necessarily indicates anything wrong with the pump. I still think the noise is directly caused by air venting, not by the pump itself, hence my interest in others findings.

It appears to be a pretty common issue.

Good explanation, although mine (V8) has never had positive pressure: always a lower pressure than ambient.

The first thing I would do is check the solonoid on the valve on the charcoal canister and maybe that nobody has dicked around with the hoses ie there is still a hose from the canister to the plenum and no blocked up hose from the tank . Just get a pos and neg and see if it clicks, and maybe blow through the valve. BE SURE TO DISCONNECT THE WIRES FROM THE ECU before doing this.

I have a LR tank so that may influence the pressure build up. I used to worry about the neg pressure too , but the engine has never faltered. If it got bad the engine would cut out.

The most likely cause of whining is the fuel pump . Does it happen immediately it starts ? If so fuel pump. IMHO an air leak would be more like a high pitched whistle than a whine.
Regards Philip A

If it's the fuel pump it'll scream with the ignition on but engine turned off.

Only for 3 seconds.
Regards Philip A

PhilipA,

It only happens at low throttle openings after driving around town for some time. Throttle openings on the highway are too wide for it. It sounds exactly like someone behind sounding a horn. It can be stopped by either taking the foot off the go pedal or pushing it down a bit.

I will check the solenoid and hoses.

Thanks for the tips.