'98 C230, 87K miles, with up-to-date maintenance, presents with inoperative power seats. Power seat relay was removed, inspected for condition of contacts (clean) and then reinserted. While slightly wiggling the relay in its socket to ensure good contact, a distinctive "pop" was heard within the trunk, identical to the noise made by a short. No smoke was observed.

The relay was removed and inspected but no evidence of shorting was noted on the contacts. The relay socket was removed, inverted and inspected; no wiring faults were found; the relay was not reinstalled. Front and rear fuse boxes were inspected for blown fuses but all fuses were found to be intact.

Following the "pop", the engine failed to start: it cranks freely but fails to catch, as though it is receiving no fuel. Plugs were removed and inspected but found to be bone dry. Spare keys were tried, to no avail. Start authorization was found to be present, when checked with a Snap-On tester.

Does this vehicle have a free standing fuel pump relay or is that function incorporated into a control module? Fuel pump leads have not been checked for power yet, but no pump whirring is heard when the key is cycled to position 2.

Any idea as to what the problem might be here? Thanks.