Is the starter turning over slowly? If so, you may never get good pressure. The starter has to spin the motor over pretty good for the IP to build good pressure.

Did you check the fuel filter in the tank? Mine was super clogged when I bought the car and keeping it from running...

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'84 300SD veg-oil bliss
'83 300SD veg-oil beater

you have old style glow plugs, in line series. the #1 often goes
bad, then the ones down line get very little juice. if your glow
plugs aren't heating then you won't be able to start this engine
without starterfluid or a shot of wd40. your could try
running a jumper cable fron the positive terminal to mid cross
wire on the glow plugs and heat it for 20 sec.

your secondary fuel filter (canister) has a air bleed on the cap.
make sure it is clear.

i think a '77 injection pump is lubricated by engine oil but if it
has a quarter sized (red) cap on it pour engine oil into the ip
there and clean the bleed hole in the cap top.

if you can sort of count the revolutions of your starter motor it is moving to slow.

don

phantom, the starter is cranking over fine, I have a boost/charger that I slap on there when I'm playing, so it should have 1200 CCA's.

Soy, haven't dropped the tank, totally not looking forward to doing that. Didn't know there was a filter in the tank.

Don, no red cap on the injector pump.

One of five is shooting fuel like 8 feet or more, it's really coming out of there, the other four are sitting there like bumps on logs. This is why I think it's the IP.
I also just changed both fuel filters, and was able to pump them back full again. After I changed them, I cracked the line on top of the big filter, and both lines on the IP, and pumped til I got solid fuel out, and then locked them back down. I did them one at a time, not all at once.