Are you getting white smoke? If it's injecting fuel you should get visible smoke out the exhaust. Unless it's cranking super slow it should fire with starting fluid if you're actually getting fuel. If there's no white smoke out the tailpipe and it's cranking at a decent speed you have an injection pump issue.
Are you sure it's good fuel?
It's possible to get fuel at the injectors when the line is disconnected but not actually deliver enough volume and/or pressure to fire. I would fit an electric lift pump and with that on bleed at the fuel filter until you're getting clean air free fuel. Once you have then, remove the restriction fitting from the top of the injection pump and bleed it there. Just disconnecting the return line from the injection pump doesn't always bleed it since there the restriction fitting/check valve screwed into the pump cover. Pull that and you've got a free path and should get fuel flow with the lift pump on. Once you have clean fuel here put the fitting back on and reconnect the return line. Be careful, if you overtighten you can snap the fitting.
Once you've done this you've should be able to bleed at the injectors. I like to start with lines very loose until you start seeing fuel and then tighten them finger tight or a bit tighter (not while cranking engine, be careful of fuel spurting out) and crank some more. Having some backpressure but not full injector pop pressure seems to help get air out.
From there you should hopefully light off or at least get a good amount of white smoke. If you've got a good cloud of smoke you've got fuel and can move into other checks.
Bottom line, if it's not something in the fuel system you should be able to fog out mosquitoes when you try to start it. If you're not getting a good cloud of white/blue smoke you're not actually getting fuel into the chambers.
