Slow filling gas tank

[Squirlye]

Every time I put gas in my truck, it takes forever. It acts like it's full, meaning the handle clicks and stops the gas. I know this supposed to happen when your tank is full. So is there a venting system similar to the ones they have now in newer trucks ? We used to have a 04
f-250 that did the same thing. But it was caused by a clogged filter mounted underneath the bed. Do these years of trucks have them ? Or it it possible that the charcoal canister is bad. Or could it be the canister purge valve? It also appears that I have 2 purge valves. One that comes off the Carb and the other one is vented from valve cover. So actually it's 2 questions, why do the have 2 purge valves ?

[ArdWrknTrk]

The '80-'86 trucks use a concentric fill tube that passes fuel around the centered vent.
While the '87- trucks send fuel down the middle, and the tank vents around that tube.

If the vent tube gets dislodged (or was never installed properly) it will cause your symptoms.

I'm saying I don't think it is the rollover valve or charcoal canister at all.

But you might want to see what others have to say.

[Rusty_S85]

80 to 86 if I remember right vents through a plastic vent hose that is inside the filler neck.

Mine clicks as well on my '82 but I am going to try and do something different on my truck when I install the 85/86 fuel tank, Im thinking about trying a larger diameter plastic/rubber hose or a longer one to get it closer to the neck itself.

I also feel that a lot of these problems cant be corrected cause my truck never had this issue it just started happening with the local gas stations going to a faster and faster flow rate on the pumps and I feel it is filling the filler neck up with more fuel than it can possibly drain and then flooding the vent tube.

[FuzzFace2]

So is this on the 86 with a 300 six gas motor or a different truck / motor?
I ask because diesels have a totally different fix, from what I seen posted, than gas.

Yes the tank fills have a vent with ion the fill hose, neck.

The plastic part fits into "holders" at the top filler & down at the tank.
I think what happens is the plastic part pulls out of the holder and makes it not work as it should.
You can see the holder at the filler side. There is the same at the tank side.

Of my picture it is what I had to make to hook up a rear tank on my flare side, never a option on a flare side.

I think what happens over time the plastic hose gets shorter and pulls out of the holder(s).
When I did the fitting of the rear tank fill I made the plastic hose a little longer so I hoped it would pull out. I may have done that on the front also but I don't remember at this time years later.

I have also seen other posts where the plastic hose has pulled out of one end or both or in 1 case was folded / pinched so it could not pass air.

Now I have also seen it posted to use the later year fillers, 87-92?, as the fuel goes down the center hose, its a little larger than ours, and air up the out side hose.
I am sure someone can post how this is done.
Dave ----

ps I should note that I may have it click off a few times but I would say 99% of the time I can fill as fast as the pump will pump.

[ArdWrknTrk]

Dave, but then you need the '87> tank as well as the filler 'cup' that bolts into the side of the bed.
I don't think there's any interchange.

The diesel trucks have an 'open' (full flow) rollover valve, because it isn't nearly as volatile as gasoline.
Diesel goes down the hose unobstructed, and the tank vents out the top.

[FuzzFace2]

As for the roll over vent at the top of the tank and the vary small line / hose all the way to the front under the battery tray where the canister is that collects the vapor.
The canister(s), 2 if duel tanks, has a hose that also goes to the carb bowl vent and a tee to a vacuum supply to clear the canister(s) when the motor is running.

There is no way this evap system can take all the air being displaced when filling the tank(s).
Dave ----

[FuzzFace2]

ArdWrknTrk wrote

Dave, but then you need the '87> tank as well as the filler 'cup' that bolts into the side of the bed.
I don't think there's any interchange.

The diesel trucks have an 'open' (full flow) rollover valve, because it isn't nearly as volatile as gasoline.
Diesel goes down the hose unobstructed, and the tank vents out the top.

I have not looked into the later fill hose hook up to our tanks but guys have done it, wonder how they do it?
I do know if you use a later gas tank because of say the in tank fuel pump there is no way to hook up the plastic inner hose. I also don't know what they do about it?

I have not looked into the diesel side other than I know when filling diesel fuel it foams a lot.
That seams to be a big issue for the diesel truck guys and the pumps clicking off.
Dave ----

[85lebaront2]

Just be glad you don't have a dually, my filler necks resemble someone's broken arm, and the front is the worst. I switched tanks when I went to EFI and used the 1990 tanks and pumps from the parts truck. I couldn't use the filler necks as they are way too short. I ended up with a pair from a Diesel 1996 Crew Cab DRW truck as all the gas ones in the junkyard had the hoses chopped so they could siphon gas for the fork lifts. Since Darth is a 1986 over 8500 GVW he never had the "unleaded fuel only" labels and restrictors.

[Rembrant]

I just bought a new vent tube for my 1980 Flareside project. I wasn't sure what to use that would be OK with gasoline, but I bought a few feet of 3/4" air brake tubing (they said it was nylon?). It will work just fine as long as the gas doesn't ruin it.

Otherwise, I'm open to ideas on what tubing to use.

[ARM Ashby]

I have a 86 f350 . I used 3/4" PeX. (RED) $1.98 for 5' at Home Depot. It handles gas just fine. You can form it to the shape you need by hand very easily.

[ArdWrknTrk]

That's great to know!

Do you have something against cold water, or the white or orange heating tubing?

[FuzzFace2]

Rembrant wrote

I just bought a new vent tube for my 1980 Flareside project. I wasn't sure what to use that would be OK with gasoline, but I bought a few feet of 3/4" air brake tubing (they said it was nylon?). It will work just fine as long as the gas doesn't ruin it.

Otherwise, I'm open to ideas on what tubing to use.

Could do like ARM ashby did and set a little in a can of gas for a week or more and see if it gets soft.

ArdWrknTrk wrote

That's great to know!

Do you have something against cold water, or the white or orange heating tubing?

It could be the red stands up better to chemicals / gas?
Dave ----

[ArdWrknTrk]

It's just color so you can figure out what is what inside the wall.
Crosslinked polyethylene is not as inert as Teflon, but it's close.

Nylon is hygroscopic. But different formulas are effected differently and have different moisture absorption limits.
If it is safety related under an interstate truck I'd imagine whichever nylon is pretty tough, but it might not be rated for immersion in gasoline or ethanol.

[Lima Delta]

I found this thread on FTE a while back when I was looking for options to repair the filler neck on my truck. I thought it might be helpful in terms of adapting an '87+ filler neck to a bullnose tank. When it comes to bending things to make them fit, it's usually helpful to see that it worked for someone else who tried it first lol
https://www.ford-trucks.com/forums/1027456-jgreen-s-pre-87-filler-neck-upgrade-success.html

[Squirlye]

This appears to be my same problem and fix. Thanks for the link, I’ll just have to start looking for some bricknose’s. I also have a front tank, I will have to do the same for that one. But for right now I’m not even using it. The tank needs to be dropped and cleaned out and new sending unit.