Replacing the fuel lines involves jacking up the driver's side of the car or better yet - put the car on a hoist. Getting the fuel line over the rear suspension by the tank , if the car is not on a hoist, can cause a few cuss words and is deserving of a stiff drink after it is accomplished. My main fuel line was so rusted inside that when we took it out - it collapsed and broke in two from it's own weight while it was being removed. Henry took an easier route with his 560sel. He placed an aftermarket in line fuel filter in his gas line near the fuel distributor under the hood. After the lines are changed -there is still crud in the fuel distributor and the screens to each injector must be replaced or carefully removed with a fine screw - cleaned and replaced (that is what I did). Run a tank of gas with fuel cleaner after doing this and if the roughness comes back a little after a while - clean the screens one more time and run a final tank of gas with cleaner in it. I suffered with this aggrevating problem for a long time before I finally got rid of it. My 560 sel now purrs perfectly. Just for the record I did all of the following in an attempt to cure it before tackling the fuel lines:
1) new plugs, wires ,distributor cap, rotor
2) took it to Mercedes for a scope of electrical
3)cleaned and checked idle valve
4) new fuel pump relay, fuel pumps, filter and accumulator
5) checked and replaced vacuum lines as required.
6) replaced defective smog pump on the off chance that circuit was at fault
7)checked engine compression
8)had timing chain and rails replaced
9) checked all emission controls items for proper operation
Remember - the fuel filter on this car is in the REAR - the fuel lines are AFTER the fuel filter-thus rusted lines will cause havoc with the fuel delivery.
HAVE FUN!!!:p :p :p