A check valve is self actuating. They either work, or they don't. They mechanically fail, or their seating can become disrupted. A selector/diverter valve, is a different story, controlling multiple portings simultaneously (or not). The problem was subject to a factory recall (dual tank) for 90,91,92, & some 93's. I seem to remember a workaround for this, but I might be confusing this w/ the later fuel system. I also think 'just call me sean" would be the guy that would have it, if there was one! I'm using a new computer, so I don't have access to my reference links (yet).

 

A check valve is purely mechanical, no electronics are required, it serves only one function, to allow fuel to travel in one direction, period. If it's broke, then it will allow fuel to flow in either direction. Nothing has to control the check valve. You can purchase them from Ford that you install outside the tank, inline, if your intank check valve fails. I don't know how else to explain this. My guess is you DON'T know how they work.

The external ones look something like this: (you'll notice there are no wires)


Also note, these are used on the RETURN line not the PICK UP line in the tank. there are several lines running in and out of each fuel tank.

 

Now that looks & sounds like a classic Ford workaround. You should be glad your not driving a Crown Vic.. 300 + Cops & civilians died before they figured out their little explody gas tank problem could be cured by grinding off a couple of frame bolts that were purposely long to speed up assembly. They would rupture the fuel cell & douse the passenger compartment w/ a 20mph rear impact, almost w/o fail. In a few of the cases, they tried to claim operator error! Google it, if you have a strong stomach. Government investigator payoffs, the whole can o' worms.

 

Let me state this again. I know how a check valve works. I build hydraulic and pneumatic systems for stationary, automotive and aircraft use that use check valves. There are different designs of check valves some are one way only all the time and others can allow a return through them using various methods depending on application.
The question that no one is able to answer is if the check valve allows fuel to travel only in one direction how does fuel return back into the tank since a FI system uses a loop/return fuel system instead of a static system that some carbed vehicles use.
I am being told here that there is not fuel selector valve in these systems that there is only a dash switch and the pumps.
Since there is no fuel selector valve then SOMTHING has to direct the return fuel to the correct tank. RIGHT! For the third time WHAT controls the return fuel to make sure it gets back to the correct tank? THIS IS ONE OF THE QUESTIONS THAT WAS ORIGINALLY ASKED?
If my question isn't clear to you then asked me to clarify it. Don't assume I don't know how an item I have been working with for 20+ years works.
DT

 

I mentioned what I call a selector/ diverter valve. On my 87', it's mounted before the fuel pump, on the frame. I believe the fuel pump circuits run through it on the way to the tank pumps. As I mentioned, I don't have access to my reference links on this computer, so I'm going off memory & whats visually accessible under my truck!

 

I'd tell you, but you sound like an *****hole.

 

He might have had some encouragement! But I'm not naming names!

 

Opppsss... My bad.

 

and could both check valves go out at the same time?? cause i have cross filling all the time in both tanks. only 20 minuites of driving and my back tank is full

 

Can you at least tell cjwat24? It was he thread to begin with & if he where logged on, he'd be on the edge of his seat! I'm pretty good at keepin secrets too!..............As long as nobody asks! Will you post it if we make DT5150 promise not to look?