I purchased a 75 300D this last fall.
Long story shortened
I have had BIG problems getting it to start.
First I came on sites like this and read archives until I was ready to go cross eyed.
heres what I have tried
Its not the fuel tank screen
Its not a leak in the fuel line
Its not glow plugs I replaced them
Its not a glow plug time relay I replaced it.
Its not a fuel filter
Its not a fuel pre-filter
It turns over good and fast and I dont think its the starter.
Its not the short rubber lines between injectors.
I have primed the lines and purged the air.
I do get fuel at the injector if I loosen the nut.
I have adjusted the valves
I have added bio-killer stuff to kill any fuel bugs.
The prefilter is nice and clear.
Let me back up a bit and describe the problem
It starts only if you plug in the block heater and its a good warm day.
It puffs some smoke out the air Intake while trying to start.
Local shop says it has bad compression.
Runs like a champ once its going no smoke and lots of power.
last owner says the odometer is correct at 78,000 miles.
I think maybe timing chain is streched out and allowing compression to drop.
just to make it more confusing it started two times in a row on a 38 degree day out of the blue and then went back to being a booger.
Can anyone help?