Hi!

I bought a locking fuel tank cap for my '05 Expedition from Rockauto. The part I ordered and received is Motorcraft FC-1004, but it doesn't fit?? I did some more research, Amazon sells the same one and claims that it fits '05 Expeditions, though in the comment section you can see several complaints that it doesn't, same as I discovered. I checked the Ford Parts site (should've checked this before ordering, but it was an impulse thing when I ordered something else, lesson learned... ), and they lists a locking cap with part number FC-1002, though I can't seem to find that anywhere...

Has anyone else had the same thought that it would've been nice to have a locking cap? What is needed to make this fit? A new filler neck?

 

Well, I was able to solve this problem, in case someone else encounters it I'm posting what I did.

I was studying the new locking tank cap, Motorcraft FC-1004, basically trying to figure out how it was put together and if I could swap the "screw neck" or what you call it from the old one to the new with the key in order to make it fit. I pried off a plastic ring around the edge of the outer cap and basically the "screw neck" fell out, revealing the internals. It's actually sort of two units, the outer ratcheting shell, and the inner "screw neck" that goes into the filler neck and seals the tank. I suspected that these were probably interchangeable, since that would be much easier than to have a million different ones for all the models.

I got the old tank cap from my truck and it had the same ring holding the screw neck in, pried it off and the screw neck fell out in the same way, and as I suspected, the internals of the shells and the way they mount together was identical, so I put the old screw neck into the new shell with a locking key, pushed the ring back into place to hold it all together, and I now have a "frankenstein" locking fuel tank cap that fits my truck! I suspect that the one I see on the Ford Parts site with part number FC-1002 is very similar to my "frankenstein" one..

Hope this helps someone else that made the same purchase as me and was disappointed when the damn thing didn't fit into the hole.

 

Just curious, why did you need a locking cap in the first place?

 

Well, there wasn't any specific need, my old cap was fine and all. But it's not uncommon here in Philippines that people siphon fuel and stuff from cars. Also, though it's rare, kids who wants to have some fun put sand or sugar or what not into the tank, so it's more of a thing for me to feel more safe when parking the truck, knowing they can't just open the fuel cap without much trouble. I wasn't specifically looking for it either, was just ordering some other stuff from Rockauto and came across it when I was adding air filters to my order and figured it wasn't a bad idea, a $30 insurance against those kind of issues.