IF you pull to try to start it....and need to stop.... you have no boost to the brakes... sure better be ready to pull against the wheel and put all your leg power into the brake pedal ...

Just last week I had to get an '80 300D started after it sat for years. The P.O. fried the starter trying to start it. After replacing the starter, I cracked all 5 injector lines, and no fuel squirting out. I used an electric fuel pump to force fuel to the lift pump, and finally got fuel to squirt out. After tightening up the lines, I sprayed WD-40 in the intake, and it fired up. The rings will seal better with something like WD-40 in the cyls in an engine that has been siting a while.
Basically do what "babyjames" said above a few posts.
By the way (aquaticedge), 1980 had no turbo, so it would be a TD, NOT a TD-T.

At this time I have no way to tow start it unfortunately.

I'll try the WD-40 trick and see if it will fire, if it doesn't it sounds like I may just need to overhaul the engine and do piston rings, head gasket, and get the injectiors and injection pump rebuilt

I wouldn't reach that conclusion without at least doing a compression test.

X2
You have a long way to go before you get to pulling it to pieces.
Best find out why it wont start first.
If you pull each GP out to test for glow, squirt 1/2 a teaspoon of ATF in each hole before putting them back in. Often that will give it a bit of extra compression & get it to go.

Will do when I get home.

Question, there isn't an electric boost pump in the tank is there?

Could it be possible that the timing is out of whack enough to not let it start properly? Also, it might not hurt to do a valve adjustment. If they are too tight it might be enough to keep them open and you are losing compression that way. Since it sounds like you have good glow and air intake, you are down to fuel delivery and compression to get it to light off.

No, unless some one put one there to help with WVO.
I really hope you get it to start so you can give it a run before you decide what to do.
Trying to start during the warmest part of the day helps as well.

Good Luck !!!

Yeah, and those are both questionable because those are both the unknowns. I don't like the fuel pressure the IP is delivering, I doubt if the IP was running like that on my TDI or 1.6l IDI that it would have the strength to pop the injectors.

At the same time, I don't know how good the compression is.

It was 89-92 this whole weekend, pretty damned warm.

Is there any way to tell if the boost pump on the side of the IP is going bad?

Given its a N/A, if you crank it over without the air cleaner lid on, you will soon see & hear if the inlet valves are too tight.
It wouldnt hurt to adjust them though, thats how I got my second 300D going after I purchased it. Much to the shock of the seller.

It shouldnt stop it from starting. It will stop it from running under load initially.
Best see how you go with the auto trans fluid or similar first.

Will do, much appreciated.

I'll report my findings this afternoon and give the valves a good adjustment too.

Progress!

Like advised, I picked up a can of WD-40 and last night I had removed the injector lines and bled the pump and left them sitting empty.

TODAY: Attempted to crank after reinstalling and re-bleeding. Fuel pressure is significantly stronger today. Added WD-40 and engine is sputtering and trying to start, still won't go but its coughing hard trying to live.

Have to let the battery charge and I'll re-report this afternoon

While you are waiting for the battery to recover, adjust the valves to eliminate that as a source of low compression.

Will do after work, I'm stuck till then