We have a 2010 fwd Flex without ecoboost. Twice we have had the flex run out of fuel after moments before showing 1/4 tank (and about 90 miles til empty). An immediate refuel shows that the tank will only hold around 14 gallons - thus confirming that there was 4 gallons or so still in the tank. I have spent hours researching this problem, and obtained the Flex factory service manual. I have collected around 25 complaints of this exact issue reported to NHTSA, or on one of the forums, and copied them to a single Word Document. There are even YouTube videos showing this taking place "live".
THE ISSUE IS, NO ONE SEEMS TO TELL WHAT THE EVENTUAL SOLUTION IS/WAS!
I understand, and have seen, the saddlebag tank system and there are 2 float sensors whose readings get combined. I understand it is possible to enter some diagnostic mode and even see the separate readings. One source of confusion is that the driver's side sensor and pickup (part # 8A4Z-9275- is referred to as a "fuel pump" when, in fact, it doesn't appear to have a pump at all. It appears to be a simple support for the float sensor and a connection to the real fuel pump on the other side. It appears as though the bottom of this component has a fuel strainer (screen) and a possible "check valve". This is just a guess based on the images I have seen. This pickup assembly supplies fuel to the REAL PUMP (on the passenger side) utilizing an internal tube/hose inside the tank. I'm guessing that there is some issue with this pickup unit and that is why I ordered a new, OEM, one from TascaParts.com.
My research shows that folks have been posting about this as far back as 2009 - that's 9 years ago. So what's the story? Do we have a definitive cause and cure for this problem? Also, I have seen a YouTube video showing 2 access panels on a 2009 Ford Flex, have heard that my 2010 may only have 1 (on the passenger side) and that 2013 and later models don't have any access panels. Do we know the straight answer to this as well? I saw a factory for video on YouTube that shows changing the main fuel pump (passenger side) is a real challenge! Getting the internal lines disconnected and reconnected seems very difficult. Even if you had a floor access panel, it doesn't hardly look possible. Also, there is an internal vapor line that can cause the float sensor to hangup, or even get damaged. You have to be very careful when lowering the pump/float inside the tank. Finally, any fuel left on that side of the saddlebag will cause the float to rise and make it almost impossible to get it to go in the proper position under the vapor line.
Some of this information shows why one person may get a pump replaced without dropping the tank and why other dealers will not attempt it without removing the tank. I think I'm going to try changing out the driver's side pickup/sensor unit. Hopefully my 2010 will have 2 access panels and that will permit me to change the simple unit without dropping the tank. BUT I'M STILL GUESSING!
Does anybody have any information on what was done to actually repair the problem? I can understand why a dealership, if they drop the tank, would want to replace both units; but that's just trying to cover all the bases with the hope they will "git er done".
I did cross-post this to another flex forum as well.
Edited by Ferrofab, 24 March 2018 - 04:30 PM.