I've tracked my '91 240 DL no-start problem to fuel delivery. First, I replaced the fuel filter to start with a clean slate. When turning the key to the 'on' position, I can hear the fuel pump relay click in the passenger footwell, and I can hear the in-tank pump priming. I confirmed this also by jumping the relay block as well as the #4 and #6 fuses. In no case have I heard the external main pump turn on with the key. I thought before I hassled with the main pump, I'd check for voltage. With the key on, I did not get 12 volts to either the black or yellow wires (I only had my test light with me at the time - no volt meter). Does the main pump get power from someplace other than the fuel relay that powers the in-tank pump? Keep in mind, this was only with the key in the 'on' position. Must the engine be cranking before the main pump energizes? I'd like to narrow this down before I start throwing parts at it.

Short version: in-tank pump is working - exterior pump apparently is not. Is a new pump certainly in my future?