Fuel pump - rattling at idle.

[groovebox]

Hi - I'm new round these parts...

OK - actually have a TOYOTA Cavalier - which I am lead to believe is a rebadged Chevrolet Cavalier. (Correct me if I am wrong.)

Basically the car (80,000km) makes a rattling sound (mechanical rattle) when idling. The rattle may still be there when driving but I can't hear it.

My mechanic looked at a number of things (timing chains, tappetts, engine mounts, exhaust and so on) and finally removed the fuel pump - using a new fuel pump the sound quitened down a bit but is still present.

He took the new fuel pump out and constructed a crude test involving the fuel pump sucking gas out of a bucket and the sound disappeared completely. Refit new fuel pump = rattle comes back. (Not as loud as before but still evident.)

It sounds mechanical (eg: metal to metal) and to my untrained ear - sounds like tappetts but he again took the fuel pump out as a demonstration and sure enough the rattling stopped again.

He suspects the "carriage" that holds the fuel pump but we are both at a loss. The car drives normally and handles as it should. He used the "screwdriver to the ear" trick and the sound is definitely loudest when the fuel pump is installed and we "listen" to the fuel line.

We have already replaced a few parts along the way and applied sound deadening material to the fuel tank. We have spent a LONG time on this one annoying problem. The only solution is to turn the volume on the stereo up!

Any and all comments appreciated.

Thanks for reading.

BB