Learn Me: Ford Fuel Tank Selector Valves Operation.

So as some of you know the fuel tank selector valve appears to be acting up on my van (90 Ford E250)

It's been leaking out the charcoal canister and the tanks magically fill up. It seems to be more of a case of the rear tank filling the front.

I've researched the sector valve but I have a limited understanding of it.

I've seen some videos where people clean them when they've become sticky.

What I don't comprehend is how the selector valve works. Is it possible for the return line valve to stick thereby causing the front tank to fill up?

Also are there any kind of outings that may have failed allowing fuel to leak past?

Note the van runs fine off either tank and the problem is intermittent.

Is this the type of selector valve with split pins going into a round one?  If so, they get squeezed together and fail to make reliable contact.  They can be VERY gently pryed apart to help resolve the issue. 

In reply to GeddesB :

I don't think so; it's A big round canister with 2 inlets and returns for each tank for a total of 4 on one side and an inlet and return on the other.

It uses a diaphragm to lift the plungers to select the tank.

My Lightning has one of these. Unfortunately, I have a similar amount of knowledge to you. 

I'd browse the Ford truck forums. Just on my Lightning FB group this thing gets talked about a lot, so it's a common problem.

In reply to ddavidv :

The Ford Truck forums had some decent information but nothing really in depth.

Changing out the canister doesn't look difficult. Some folks even clean them up and reuse them.

At this point I'm going to take the van into a shop I use; the tanks are full and the valve is below tank.............I don't relish a gasoline bath. I'd venture to guess a shop can do it in under an hour.