Noisy Fuel Pump? R129 500SL

[LeaUK]

Hi all

Last week I had an odd incident where after an hour or so of motorway driving I stoped for an hour. Then she wouldn't restart. As the ignition was turned on to just before the start position I heard a weird gurgling/rumbling sound (very difficult to explain) coming from the rear of the car and I'm sure I didn't hear the normal tinkling of the injection pump.

Several start attempts and still nothing, or at the very most the occasional fire. The solution was to depress the pedal just after start and finally she started.

I then drove for a further 45 minutes and exactly the same symptoms persisted ie, she failed to restart but no gurgling sound but I'm sure that the injection pump when running was loader than normal!

I filled the tank up to full where it had been previous around the 1/4 mark (which it has never been before) and all is now well again.

Would an airlock in the fuel system cause these symptoms? Is the fuel pump on the last leg? Are there any simple tests as a user I can perform?

Any thoughts or suggestions most welcome.

Lea