My 1985 740GLE when I try to fill the gas tank I immediately get splash back the minute I turn on the pump. It appears that here is a second flap part way down the filler pipe which will not get out of the way. Anyway to fix it?

Hello,

"I immediately get splash back"

I usually get that when the tank is full. Jokes aside, I think the fill nozzle should be kept almost horizontal during filling. I can see no second flap or fuel door inside the fill pipe from my 740 parts diagram. Another possible reason is that the fill nozzle has been pushed too far inside until it reach the pipe's bend which made you think likely a second fuel flap.

Amarin

I pushed a rod part way down the pipe and felt an obstruction. Push a little harder and it gave way. True the pipe doesn't show it because it's internal. I think its there for one or 2 reasons: 1. stop anyone from steal gas. 2. In the parts diagram that I see when I look at the site for old OEM parts there appears to be a some kind of pressure balance system that connects to filler pipe lower down.

Does that year/model have a roll-over safety valve? If so it may have been stuck in the up (closed) position. How it would get itself into that position is a another question.

Yes, according to the Volvo parts diagram there is a safety rollover system. However I think its an anti siphoning flap. A soft rubber hose will not move it. When I pushed a flexible nylon rod a short way in I could fill the tank from my 5 gallon container. This would not work at a gas station because the rod would be blocking the intake pipe where the hose goes.

maybe there is a twist in it somehow?

There is no twist. The pipe is straight and appears to have no kinks.