Hi,
Instead of the glow plug resistor use a 50A fuse

Fuse A000 545 25 34
Fuse Box A123 540 04 50
Did you replace the 3 metal loops between the plugs with wires?
http://dieselgiant.com/mercedesdieselloopglowplugrepair.htm


I had the same problems and that`s what I did:
---Replaced ALL the rubber fuel lines from engine to tank-easy task,they were 40-y`s old anyway...the small feed line from the tank to the feed line had different diameters on each side and had to be bought from the dealer and was pain to replace...just leave it.)
---Removed and inspected the lift pump.Changed the original hand pump with the new style one,tightened WELL. Checked and cleaned the 2 valves,some rusty particles from the tank,the 2 o-rings were o.k....Removed and checked the relief valve on the inner side of the IP...
---Got rid of the original aluminium primary filter assembly and installed a transparent ordinary Mann ..
---Checked all nuts and bolts on fuel lines,filter,pump...
However,after priming the hand new hand pump(what a difference!) there was still some air in the primary filter...tapped it hard,primed again(all this several times) until no air was visible in the filter.Now even after a month the hand pump is firm...
Before reinstalling the lift pump,rotate the engine by hand in such a way that the IP cam lobe is not in contact with the lift pump plunger for easier tinghtening of the 2 nuts...And change the oil in the IP .Total costs: appr.25$
P.S. You do not need a time relais.Keep things simple.You don`t need the resistor either...Just get the correct gauge wire..And the fuse..