I read briefly about this mod right here last week. My truck is a supercab short bed and I have a rather small fuel tank. In the past it would only take 22-23 gallons of diesel until it spit fuel all over me and the side of the truck. Well this weekend I dropped the tank, reached inside and cut off the 5" long PVC vent hose. I also did the pre-pump mods but that is a story in itself. The whole job was real simple. Then I went to the local station and promptly put 31.8 gallons in it. That was the first click off and their was no fuel spilled on me. Now my truck has been stuck on way past full for over 100 miles!!!
Best mod I've done yet.
Unfortunately my fuel line spotter didn't do his job and I had a pinched fuel line and we spent hours towing me back and screwing w/ it. That added about 5 hours to the job. Oh well.

 

harpooned the tank? enlighten me plrease

 

Well the way I understand it, it works like this.
Diesel foams when agitated and expands when heated. Ford had the brilliant idea to protect us from ourselves by putting a 32 gallon tank (on my configuration) but extending the vent hose several inches into the fuel tank. This results in the foam (that is temporarily created as you fill the tank) reaching the vent hose and blocking off escaping air. You attempt to put more fuel in and the air has no where to go so it burps back up at you and generally brings a bit of fuel with it. On my truck that point was about 22 gallons. It is obvious that this is all the fuel that Ford intended for me to put in this tank since the fuel gauge is definitely at FULL at this point. Others have discovered that they could put considerably more fuel in the tank if they spent the next 10 minutes or so putting the fuel in rather slowly. I'm pretty lazy so that's not going to happen w/ me.
Someone on this site mentioned this mod about a week ago and I've always believed that any source of info must be a good source so I dropped my tank this last weekend and snipped off the 5" of PVC pipe that is connected to the vent hose. I really didn't think it would make that much of a difference but I went down the street to fill up and my truck took 31.8 gallons quickly and efficiently. In fact, when the pump shut off it did not even spit fuel all over me. I did not force the issue by attempting to add even more fuel. The mod only took about 2 hours or so total and about 30 seconds to snip the hose.
I understand that the guys w/ the bigger tanks have the same issue just the #'s are bigger.
A word of caution. I would not attempt to squeeze every last little bit of fuel into your truck and then immediately park it on a hot day w/ out using some of the fuel first. There was a story about a guy who did just that on a hot TX summer day and came out to find his truck overflowing w/ diesel coming out of the filler cap. That would be a bad thing. Diesel can expand up to 5% if it is heated enough.

1.) Get the truck nice and low on fuel.
2.) open the fuel filler door and undo the 3 -7mm screws.
3.) under the bed, remove the filler tube and vent hose from the fuel tank by loosening the hose clamps.
4.) loosen fuel tank brackets and lower the tank using jacks or whatever, just 8" or so.
5.) reach to the top of the tank and disconnect the fuel pick up line, the fuel return line, and the fuel sensor connection. (you will need a quick disconnect fuel line removing tool to do this, available anywhere for about $3)
6.) Unscrew the plastic cap that holds the sending unit. Carefully remove the sending unit. It is ceramic and can be broken easily.
7.) set that out of your way and do not disturb the float assembly. If the umbrella shaped piece of plastic falls off of your sending unit just reach into the fuel tank and carefully stick it back on to the sending unit.
8.) peer into the tank and snip off the 5 " pvc pipe as close to the top as you can. This left about an inch for me. I used a little hand held tool that was made just for snipping PVC pipe.
9.) put it all back together. The plastic cap for the sending unit is a real pain to get back on. I stuck mine in the microwave and greased it up to coerce it back on.
Good Luck guys.

 

wow that sounds cool. ive got the bigger tank so when i get to it itll be cool. thanks!

 

What year truck do you have?
I'am just curious as I haven't ever had fuel burp out at me.
My only complaint is guage say's empty at least 100 mile before it really is.

over and out
gseeders

 

I have an 89 diesel and I don't have the burp of fuel when full BUT I can only squeeze the nozzle a 1/4 or so to keep it from kicking off. Its rather annoying. Especially when there are people waiting on you to get done. Maybe I'll spend the time to snip mine off.

 

My truck is a '99 Superduty.
I understand that this is what is slowing down the fill process on the older models as well

 

Okay, so let me get this straight. You snip off the few inches of tube that is sticking down into the tank, or do you pull out the whole tube?

 

Snip off as much of the PVC vent hose as is reasonable. I ended up w/ about 1" left because that was as close as I could get w/ my tool. I suppose you could attempt to get closer but I wouldn't want to push it. I was told to"cut it all off."

 

Has anyone tried to just pump the fuel in at a slower speed? Just curious. I have only filled mine up once and it is annoying to sit there and keep pumping a little bit at a time.

 

I always set the pump handle on the first notch. Walk around the truck check tires, lights (If it's dark outside), check the oil level and antifreeze level. Usually it take 25 gals. Not a problem with me. Wife doesn't like it because I have to always go in and pay for it cuz its not a pay at the pump and also it's a diesel. That doesn't bother me tho I like it! I don't like her Acura, no room for my 6'2" 235 lb. frame.
over and out
gseeders

 

"I don't like her Acura, no room for my 6'2" 235 lb. frame."

I know exactly where you are coming from. I am 6'2" also and around 200lb. My wife drives a Del Sol right now. she just doensnt understand why i dont like to drive it.
I had a 00 ranger before this and it wasnt that great for room either.
With my Superduty, i dont even have to scoot the seat back all the way!

 

I always just stick in the nozzle and go as fast as it will pump. Only 3 or 4 times have I had it "burp" at me when finished. I guess if the tank will hold and extra, what 2 gallons maybe it would be worth the time.

 

Does the fuel tank mod cause the overhead display showing avg. miles per gallon and miles to empty to be inaccurate? I'm not sure what it uses to calculate this numbers.
Picard

 

Yes.
Someone on another board stated that they had their chip reprogrammed to compensate for this.