TLDR: one short section of fuel hose, which is a separate piece of hose connected to a longer run, disintegrated internally after sitting for a few weeks.

Here's a weird one. I've been rehabbing my '82 Alfa GTV6 for some time, and over the past few weeks have finally gotten things to a point where I wanted to start it up. I added gas and began prepping it to drive.

Except it wouldn't.

I traced all of the ignition wiring and fixed a couple of iffy grounds, checked fuel pressure, then realized I'd wired the fuel pump (it's external, under the car) backward, so it was running in reverse. OK, not a huge deal, as I'd only cranked it a few times.

The car is Bosch L-Jet, so there is a master relay that fires up the pump and the injectors based on the position of the AFM in the airbox, so you can jam a long screwdriver in there to imitate a cranking situation without cranking the starter. No sound from the pump at all, even after rewiring. Normally it hums audibly.

I pulled the pump, and that's when I realized one small section of hose that attaches it to the tank had internally disintegrated into a sticky black goo. 

I'd replaced the fuel lines several years prior. The kit included a long length of hose from the tank, but the end section that connects to the pump was a separate piece of hose joined with a plastic coupler, because it's a 180 degree bend (the line loops around... it's a weird setup but apparently has to do with the gravity feed). ANYWAY, that's the ONLY section that's affected. 

I went ahead and drained the tank and pulled it, and the gas was clear with nothing in the internal sock/filter. The long length of hose was fine. The  hose between the pump and the filter was fine. The injectors were fine. But the pump was toast, totally filled with the goo. Thankfully I have a spare (who owns a classic Alfa without a small storehouse of spares on hand) so now I just need to rebuild the hose, install the pump, and try again.

All I can figure is that piece of hose was not ethanol friendly OR it had to do with the pump running in reverse for those few seconds I cranked it. Neither makes a lot of sense but I'm leaning toward a chemical reaction with the ethanol in the fuel.

Anyone experienced something like this? The image is a toothbrush pushing the goo out. It's too thick to squeeze out but too thin and viscous to grab with a tool.

One section of fuel hose melted