I'm going to assume you're more familiar with the 200 series than you are with the 700 series. Some parts are in differant locations, so if I repeat anything you already know, I am not attempting to be condescending.

The first thing I would do if you beleive it's a fuel delivery issue is disconnect the fuse to the in-tank pump. It should be the right-most fuse on the top row. The fuse panel is located behind the ash-tray. After removing the fuse, I would then pulse the starter once so the pump will run for a couple of seconds. The main pump located under the driver's seat (on the bottom of the car) should make a buzzing or straining type noise if it is clogged. (Someone please correct/chastize me if I am mistaken. Mine makes this noise.)

If that is inconclusive, reconnect the fuse and disconnect the cable from the air mass meter. Crank again. If it starts, reconnect the AMM. If the engine dies, the AMM is t0zed. If it tries to die and then surges, it's OK. Of course repeat to your liking before condemning.

You may also want to check the start inhibit switch in the gear selector. Also, make sure all your fuses are good, especially the one on the top row all the way to the left. There's also a relay clipped next to the radiator expantion tank. Give her a good thump.

If I've covered anything that's ludicrous or violates everything the universe has ever shown you, please don't be afraid to flame me in correction. :)
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89 764 GLE 150k/ 86 745 GLE 240k