Help removing rear fuel tank in 87 F-250?

Basically the issue is that something is wrong in the fuel system so the truck runs out of fuel after a few minutes (even though there is plenty in the tank). I removed the front tank and the pickup was cracked and falling apart, but the rear tank is full and too heavy to get out without draining it, but I am stuck on how to get the fuel out. 

I can't get anything in the fuel filler to do it that way or reach between the tank and the bed to disconnect it, and it's parked facing uphill on my sloped driveway and doesn't run so I really have no way to get the bed off.  It's looking like the only option is to punch a hole in the bottom of the tank and drain it that way and just get a whole new tank, but it seems like there should be some other option. 

I'm really not sure what to do, it took almost a year to find this truck and i still need one, but also I have owned it since last August and still haven't been able to drive it and I think I may have run out of skill to get it back on the road, it might be time to abandon this project and try again with a Chevy or Dodge because apparently every Ford has this issue with the fuel tanks.

Can you jumper the fuel pump and use that to drain the tank? Like if you disconnected the fuel line somewhere you have access now?

Sorry I forgot to mention it's a diesel, so it only has a mechanical lift pump on the engine.  I could try to hook a transfer pump to the line coming out of the tank and see if that does anything, I had that idea after I worked on it last so I will try that tomorrow.

Siphon.

Extend the fuel line from the tank to a level below the bottom of the tank. Apply suction to the fuel line. Some kind of little hand operated pump or siphon hose should work. Once the flow is started, it should keep going (slowly) by itself. Make sure you have a container big enough for nearly all the fuel in the tank.

Examples / suggestions/ideas are below. You do not have to get this hose into the tank. Just attach it to the hose or line that comes from the fuel sender assembly. Use hose barbs, size adapters, wraps or tape as necessary. It's just temporary.

Use an air gun on a siphon hose.  Blow air across the open end of the hose and use Bernoulli to your advantage.

The thing most people overlook is that removing the bed is not nearly as bad as it seems.  Pull the taillights, unscrew the filler hose, 6 bolts, and have 2-4 people help you walk the bed away.  Bingo.  Easy access to everything.

Before you go to that trouble, I assume that you verified that the lift pump on the engine can pull fuel from a hose.  The diaphragms on those can and do fail when they get old.

Pulling the bed is not too terrible, usually, and it doesn't have to come OFF, just UP enough for access.  With lots of safety supports of course, since your squishy self will be between the bed and frame.

I plan to change the lift pump as well, but the truck sat for years before I got it and the pickup in the front tank was literally crumbling, so I suspect that the rear one looks about the same.  I honestly don't know anyone would would help me pick up a truck bed, so if I do have to remove the bed I'd be stuck using an engine hoist.  I guess the only other thing I can try is to see if I can siphon or pump any fuel out from the fuel line, I guess that may show how functional the pickup is too.

Tk8398 said:

I plan to change the lift pump as well, but the truck sat for years before I got it and the pickup in the front tank was literally crumbling, so I suspect that the rear one looks about the same.  I honestly don't know anyone would would help me pick up a truck bed, so if I do have to remove the bed I'd be stuck using an engine hoist.  I guess the only other thing I can try is to see if I can siphon or pump any fuel out from the fuel line, I guess that may show how functional the pickup is too.

It's easy to lift a truck bed with an engine hoist.