Recommendation #1 --
DON'T continue attempting to start the engine or drive the car.
Something is wrong with the engine and you could do more damage by continuing to attempt to operate it.
The right move is to STOP attempting to start it, and instead figure out what the problem is, using an organized process of diagnostic steps. Once the problem is found and fixed, the engine will be ready to run again, assuming no lasting harm has been done (cross your fingers).
Now -- on ideas for what the issue could be. I think your guess of incorrect injection pump (or cam) timing is the most likely answer. Sudden onset of difficult starting, excess smoke, and poor performance/noise is classic textbook symptoms of a slipped/stripped timing belt or timing gear.
Your first move should be to look for damage to any of the timing belt components from the accident. Did anything involved with the front timing belt cover, water pump, etc get hit or moved by the damage?
Second: remove the front timing belt cover and inspect the front timing belt. Check it for damage, stripped teeth, loss of tension. Check the water pump pulley for radial play. Check the crankshaft accessory drive belt pulley for rotational slop. Put a wrench on the big bolt with the 27mm head on the front of the crankshaft and attempt to turn it backwards, to see if it's loose. If it is still tight, rotate the engine either direction for a few full turns so that you can inspect the entire front timing belt, and make sure the engine turns as it should.
THEN, repeat these steps for the rear timing belt, checking for looseness, stripped teeth, damage.
THEN, assuming you haven't found an obvious issue already by this point, do a basic visual check of camshaft and injection pump timing. You want to find the notch on the outer flange of the injection pump drive gear (use your finger to feel for it if you can't see it visually at first), then rotate the engine by hand until that notch starts to approach the notches on the injection pump bracket and case. As they start to get close, begin looking in through the opening at the bellhousing to watch for the TDC mark on the flywheel. Turn the crank slowly until you see the flywheel TDC mark (it's a "0" I believe?) lines up with the arrow in the bellhousing. Then, look again at the IP gear and see if it's lined up with the notch in the bracket. For more details on this process and photos/diagrams of the areas you need to look, try searching and reading threads here on the forum about timing belt replacement, or you might want to buy a copy of the Volvo D24 "greenbook" factory service manual (usually about $20 on ebay and a very helpful resource to have).
I bet it will not be lined up and that will be your issue. If that is the case, then your next step after this will be to figure out which belt slipped: the front or the rear. Either it's just the IP that's out of time, or it's both the cam and the IP (which is driven off the cam). Cross your fingers it's just the IP, as loss of cam timing usually result in engine damage -- could have been the loud tapping you heard after starting the engine by shooting fuel into it.
Once you get to this point, let us know what you have seen, and we'll advise on the next steps to figure it out. Or, in the event that you confirm the timing is OK, we can move on to different possibilities, although based on your symptoms that is highly unlikely.
Good luck and welcome to the forum -- sorry to see things start off with problems but hopefully we can help you get it figured out and back on the road.
