CLS500 07 intermittent power to fuel pump

[Bikeybob]

I have been struggling with an intermittent problem with my CLS500 5.5L.
Starts and runs great then from nowhere I will go to start it cold and it cranks great but no start.
Replaced CPS with new genuine. Still fails to start then comes good.
Tapped into the wires running to the fuel pump under the LHS rear seat and fitted a small lamp as an indication.
For days it gives the light for 2 seconds on key on then light back on while I am running.
I note if I stop the motor then go for a restart I do not get the 2second pump run but pump starts fine on cranking.
Now nothing. No pre start run. No run on crank.
I think the fuel pump relay is ok. Tested with a meter. Fuse looks ok.
No check engine light.

No doubt it will come good again.

Any ideas. Regards Bob

 

[mattkh]

I do not have a CLS500 or the wiring diagrams, but here are a few pointers.

Ignition switch especially with a heavy bunch of keys on the key ring
If there is such a thing on your car, a fuel pump cut off relay
The fuel filter
The electrical connection to the fuel pump.