I have a 2011 F-150 STX 4x4 with roughly 99K. It has a 3.7 Liter V6 and has been doing something weird. I can go from 180 miles to “low fuel” in about 8 miles, despite having plenty of gas in the tank. I have also noticed that when I fill up, and try to start, the engine turns over but acts like it doesn’t want to fire. If I pat the gas a little it fires and runs okay. This ONLY happens when I fill up with gas, regardless of how much gas I get. The miles to empty seems to dwindle down to low fuel almost every day. If I stop, turn off the ignition, then crank up, the miles to empty appears as it should with the amount of fuel that is actually in the tank. Any ideas or suggestions??

 

The only thing I can think of is a bad fuel sender. What happens is if it's sticking, it could be registering that resistance value for 180 miles or whatever and than once it drops or moves, it gets down to the right position. One thing you can do is next time you fill up, note your odometer mileage. Then, see what a typical tank gives you. Next time it registers 180 miles, see what the odo reading is just to see how much fuel you really have. My bet is still for the fuel sender as they are finicky.

 

Thank you! Is the fuel sender difficult to swap out?

 

Fuel sender is usually in the fuel tank. So you'd need to drop the tank and than remove the attachment screws / locking ring and then pull sender out.

Here is what a typical sender looks like: https://www.carid.com/2011-ford-f-15...250857280.html

Usually the float is the issue.

 

try running a couple cans of Berryman's B12 through it, might clean up the contacts if they're gross. Definitely cheaper/less effort than dropping a tank and swapping things out. If a couple runs of different chemicals don't sort it out, you're not out a whole lot.

If it does sort the problem, you just saved a pile.

do the easy thing first.

 

Thanks! Where can I get some?

 

most any auto parts store, on the shelf with all the carb cleaners.

 

Picking up some tomorrow! Thanks again!
Chris

 

You have a leaking fuel tank purge valve. It is causing vacuum in your tank making it hard to start, especially after filling. It also bows in the tank and pushes on your fuel sender.