Friday morning started my 71 240z; ran rough, then worse, then died and wouldn't restart (car is driven daily and recently completed a 600+ mile two day rally).  Starts with starter fluid.  No fuel coming from mechanical fuel pump output when engine is cranking.  Decided that fuel pump had failed. 

Saturday replaced the fuel pump, fuel filter and a couple of sketchy looking fuel hoses.  Still wouldn't start.  Added 8 more gallons fuel, did not help.  No leaks seen.

Today connected fuel bottle to inlet side of fuel filter, car starts right up.  Filter and pump are now known to be good.  Connected electric fuel pump to line feeding the fuel filter; no gas seen at pump outlet.  Tried compressed air from fuel filter inlet back to tank, no bubbles heard, only fumes from filler neck.  Seems like the fuel level in the tank must somehow be lower than the pickup?

Additional: DPO installed a 280z tank in my car.  Tank is dented, can see pinched hoses.  Maybe should start with a known good 240z tank and work from there?

Thanks for looking at my post!

You could try eliminating the chassis fuel lines as a variables first. Might prove the tank is actually fine. Connect the tank out barb to an external fuel hose running to your now known to be working fuel pump. Does fuel pump to the pump outlet? Since you have a mechanical fuel pump it means you will need to buy a decent amount of fuel hose though. Or, might you have an electric fuel pump laying around. Just be careful working with the tank and lines and exposed fuel. Don't burn your car or more up.

 

Today drained the fuel tank completely.  Disconnected supply/return lines from tank to engine compartment, on both ends.  Used compressor to blow air through both lines, from engine compartment back to tank.  Pressurized air came out without no debris, both hold pressure.  Tomorrow will connect an external fuel bottle, located near the tank, to the line supplying fuel from there to the fuel filter.  If car starts then I'll know that the lines are good.

Chassis fuel lines are good.  Removed the defective 280z tank today, picking up a good 240z tank tomorrow morning.  Should be back to running by noon.