Originally Posted by 97 SL320

Do you hear / feel the pump running when you key up or crank?

Using a digital meter can be deceiving. If a wire is nearly rubbed through / corroded and the circuit isn't loaded, a digital will show voltage that goes away once a load is applied. Using a incandescent test lamp is the way to go as it will load the circuit.

Is there a voltage rating stamped on the pump? I'd assume it is 12 rated, if so apply 12 v directly and see if you have fuel pressure / engine will start.

If this is a returnless system, the pump is slowed down to save power / wear on the pump / heating of fuel.

Any spark at the plugs / injector pulses? If not, I'd vote for a crank sensor issue.