If the lift pump is running but no fuel flow, you can try this while deciding what else to do:
After removing the lift pump from the engine you can do a temporary rebuild following these instructions:
1. Remove the cover by backing out the three studs. It took a flat scraper to get mine to break loose.
2. The gasket along with the steel plate that holds the vane pump section in will come out all stuck together. Keep track of which side of the steel plate is to the vanes for reassembly. If you lose it, the side against the vains will have a circular mark about 3/16 in diameter where the vane holder has been running.
3. Remove the filter screen. If it's dirty, clean it. Try not to bend it from it's circular set or it will be hard to hold in on reassembly.
4. Remove the vanes and holder. Be carful not to drop or lose the vanes. You don't want them scarred or scratched on the rounded edges. If the rounded edge has become flat, flip the vane on reassembly to get a round edge against the inside of the run.
5. With a pair of needle nose pliers, gentle turn the shaft of the pump. It's the flat thing you see after removing the vane holder. It should turn freely.
6. Reinstall the vane holder and then slide the vanes into the holder.
7. Install the flat circular steal piece over the vanes and reinstall the filter screen making sure it's all the way in.
6. Flip the gasket over. Reinstall the gasket flipped over from the way it came out. Its easy to see how it goes. There is a curved indention in the gasket from pressed into the pump body. That will go up or against the cover plate on installation.
7. Reinstall the studs. Don't overtighten but they need to be snug. Mine were loose when I removed them.
This takes about 15 minutes to do the quick rebuild. Flipping the rubber gasket/seal will get your pressure back IF the motor still works in the pump.
To bleed to the fuel filter, just open the water drain on the side of the filter and bump the starter. If fuel squirts out, you have fuel to there and the lift pump is working.
Good luck. By the way, I did this myself and so did a couple of others and it can work, assuming the motor is OK and there are no broken parts. Also, that little screen in there can get stopped up and no fuel will go through.
You can search the second generation forums, Alan Reagan, lift pump and find the post.