Ok...any cure for real slow fueling on both tanks? '84 f250 6.9idi... Have to trickle it in...cannot even go with the first notch on the fuel handle.

 

Could be the vents in your filler hoses are gone, damaged, or have fallen out of their keepers as described here https://www.ford-trucks.com/forums/1...86-5l-efi.html I did a write up recently about making some out of copper pipe or PEX. I know this issue is worse on the diesels as the fuel foams up.

 

Are your fuel tanks original? If someone worked on the tanks and they didn't assemble the vent tubes properly they won't fuel well at all. Even with the vent tubes properly installed don't use the high speed pumps that big rigs use for fueling. The nozzles are too big and even on the first click they will quickly overwhelm a properly vented tank. On my 86 IDI it's impossible for the vent tubes to "fall out". The only way I can see that they don't work properly is miss-assembly during a tank replacement.

 

Tanks are all original...will be dropping front tank soon to replace sending, draw and return line assemblies... Diesel.

 

My 82 cant fall out either, it has a ring that the vent tube slides into and it just lays at the top near the filler neck opening. Mine even has slow fueling where you have to go about 1/2 on the fuel pump due to how fast they pump now. Ive been personally thinking of doing the upgrade to the later model fillers that so many people on here have done. not sure how well they would work on a flare side tank and filler hose. I actually thought of knocking a hole in the tank up near the top and attaching a barb fitting to run a fairly large external vent up to the filler neck near the filler neck opening as an alternative.

 

Maybe a PO dropped the tanks to replace the sending units before. And didn't re-assemble it correctly. The original sending unit usually lasts for about 200,000 miles or about 20 years.

 

Yes...the vent tube fits in a support ring at the tank and tucks up above the filler neck baffle. I've not experienced any problems filling mine on the first click or slowest setting on most pump handles.

 

Only problem I ever had was that initial start on the pump even just barely applying the air hasn't found its way out and it does cause a back up and click the pump off. Second go its all fine. Its why I am thinking of trying the later style upgrade where the fuel goes down the center hose and air comes back up around it. Might be a better option for me long as the center fill hose would be long enough to fit the curves of the flare side filler hose.

 

My truck is style side with dual tanks. You have a slightly different filler hose arrangement making fueling a bit more difficult with the flare side. Still I'd resist any temptation to punch another hole in the tank, especially if the tank fills properly after that initial burp.

You could post a question on the 87+ page and see how the flare sides like that filler arrangement. With luck it might be a direct fit. Just order new parts and plug em in?

 

I think mine does the same thing. I wonder if the vent has fuel sitting in it from the last fill up.
When you start filling the air has to push it out of the way and think it drains back into the tank and you are good to go after that.

Both tanks on my flare side (yes that is right both tanks on a flare side) fill pretty fast but I find when the rear tank gets about 12 gallons on the 19 gallon tank it will click off and I have to go slower till I know it is full.
Most of the time I run both tanks down to about 5 gallons left in them and I fill the rear tank first so I know how much it should take. The front 16 gallon tank has no issue clicking off a few times when close to full like the rear tank does.
Dave ----

 

The guys with the gasoline trucks have some problems with this, but the diesel guys like the thread starter have a terrible time, the fuel foams so bad. Very bad problem with the diesel trucks. My 89 diesel was terrible also.

This is a special fix for the diesel's only;

If you do some research, you will find many "fixes" for the problem, I tried most of them will little improvement. What finally fixed mine where I could actually fill with at least 1/2 speed at the fill station was to modify the venting in the tank. When you pull the tank, you will see a plastic fitting on top with a short hose on it. This is a vent to let air in when the engine pulls the fuel out. The plastic thing is a roll-over valve.

I pulled the rollover valve out, and re-using the grommet, I installed a 3/4 copper elbow into the grommet. It's what I had laying around and it fit snug in the hole. I then soldered a short piece of pipe to this, and then using a hose clamp clamped a rubber hose onto this pipe and ran it over to the side of the truck. I then ran it up high beside the bed and then tied it up with a piece of screen over the end to keep the bugs out.

This works wonderfully, the fuel will go right into the tank. The only problem I have with it, when the fill station fills the tank and shuts off automatically, my vent hose will puke a small amount of foam out underneath the truck. Other than that, no problems.

P.S. I did have one of my hoses fall down a little bit, and it got a belly in the hose. Unknown to me I discovered I was back to not being able to fill the tank. That is when I discovered the vent hose had slid down, and when I put it back up diesel fuel ran out. It worked good after that again, the belly in the hose was letting diesel lay in there and not letting the air vent out.

 

That's what I wonder too some times. I figure since I have to drop my tank anyways to install a new NOS sender I figure maybe now is the time to make the filler neck upgrade if I can source the right pieces I need. Either that or see if the plastic vent tube is kinked or anything and possibly replace it with the spare one I got from a customers '82 F150.

 

When I was at that point in my build either I did not know of using the later years or did not have the time to go yard hunting for them.
On the style side parts truck the plastic tube had fallen out or was broken, in was not where it should been. Now did this happen in the roll over or ?
I know 1 tank was not being used as it had 5 gallons of bad gas in it and later found the switching valve did not switch.

I think if I was to do this again (for gas trucks) I would use the PEX tubing in place of the factory plastic stuff.
I know with the factory plastic in place it fills pretty fast for me.
Dave ----

 

I think you're on to source of the problem...fuel stuck in the vent tube from topping off that gets burped out when refueling. This may be more of an issue on the flare siders where you may have a longer horizontal section of filler tube up to the cap? Any sag in the vent tube might hold fuel after a top off. You might try fueling till the pump clicks off the first time without topping off. If on the next fueling it takes fuel without the initial burp it probably indicates a saggy vent tube.

 

I don't think they are the same but I can always check and see.

I will have to keep the PEX tubing in mind. my black tubing doesn't seem to go up all the way to the filler neck plate but it is below the pump nozzle so it probably doesn't have an effect.