I just moved from the southeast to alaska with only suitcases and was happy to find a "nice" 4.2 liter f150 4x4 for less than 3 k....

I filled it with gas and noticed the smell of gas. I looked under the truck and saw gas on the tank. I notice that toward the very back of the gas tank on top, there is something missing. I am not a car person or even a shade tree mechanic. However i was able to see that there is an open machined hole in the top of the tank--diagrams suggest to me that this is where the " gas tank vapor valve" should go but is missing... again, this hole is machined into the top of the tank and the last thing on the tank toward the rear of the car.

I believe that my fix for this would be to purchase a new valve and seal off amazon prime for this (again im in rural alaska)? is this something a nonmechanical person could install? it appears to me i would just put the new seal on the valve and put it in the hole on top of the tank and turn to tighten. I know it is then supposed to be hooked up to the line going to engine. My goal is to get something in the hole on top of the tank so my truck wont be such a fire hazard for starters and then get the lines hooked up. The truck runs well believe it or not.

any advice or direction to old threads would be appreciated!!! thanks in advance! mauserdoc

 

Would it be possible to post the diagram you found here? Maybe that would help someone diagnose what it is.
My book does not show one. It just shows the fuel pump replacement.

The "hole" you're talking about is not located near where the fill hose is?

 

 

I found this diagram, Are you talking about #6 there?
https://www.f150online.com/forums/v8...ml#post2759789

If so that ties into the evaporative emission canister. That is located towards the rear of the tank, right around above the axle in the center.
I am wondering if someone took the whole thing off of yours?

I never fooled with mine, though I was looking at it when I was under there and they do get quite rusty I wonder if it rusted out and he just took it off altogether?

I don't know much about these, maybe someone else does and can explain its operation better?
The operation is explained somewhat in the whole thread in the above link.
Read through it, if the hole is #6 in the diagram then it should be hooked to the canister as you can see.

 

I was typing the same time as you were posting.
Yep that is it, see where it goes?

Do you still have the emission canister on the truck?

It would be up over the rear, in the center, forward of the spare tire bracket.

 

There is a tube that I assumed went to the cannister. It has the broken off piece of the vapor valve hanging out of it... It appear that if i put the new valve in, i could hook it up to that line and be good. If i get the valve in and cant get it hooked up to the tubing, I figure ill be better off than with this opening in my tank... I cant believe the truck is running and hasnt blow up yet... Im gonna drive a rental until my part arrives from anchorage on tuesday.... has anyone ever changed one of these valves with the tank still on the truck?

 

Yes--i thought it was #4 on the diagram, but If 6 is toward the back of the vehicle in the diagram, I think that would be it. 4 and 6 are labelled as the same thing....must be a valve on each end of the tank.

 

Did you click on this that is in the above post, PO455 Code?

#4 is the fuel VAPOR vent valve.
#6 is the fuel TANK vent valve.
#6 should be the rear.

Most likely the same valve?
I don't know you would have to find the part numbers, might be the same valve?

I have to research this emission canister further myself, when I was up under there I was wondering how it worked.

 

indeed and thank you for the link. the valves look the same in the pictures i have for number 4 and 6 so hopefully they will be the same. so far i cant find different part numbers. I ordered the part from a local napa and it was 20$ more than from amazon, but getting my truck SAFELY on the road 2 or more days sooner will be worth it... thanks for the input! ill post how things go when i get the part on tuesday...! in the mean time, it will be the rented ford focus for me...

 

I put the new valve in today and it stopped the leak. thanks for the input everyone.

 

It stopped the leak but did you hook it to the hose that goes to the canister?
Your canister is still there right?

I thought someone else might better explain the canister but I guess it is google time.

Springtime I want to look at mine closer and maybe paint it. I don't know what kind of shape it is in but the cover over it is rusty.
I will wait to the warmer weather and look.