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Aux Fuel Tank Filling Issues

mimmonen

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Mar 15, 2014
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I replaced my auxiliary fuel tank, fuel filler neck and hose in my 67. The new neck includes a breather tube. I also got the long neck cap. I ran one tank of gas thru it and went to fill up today and fuel started gurgling back out of the filler neck. The tank was empty and I probably only got 1/2 gallon in. Went home pissed off and tried pouring fuel in the tank from a 5 gallon can. Same results. Any ideas on what to check?
 

Broncobowsher

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Jun 4, 2002
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Picture of this breather tube please.

For fuel go get into the tank, air has to leave. If it is in the same path it will spray back at you. I never owned a factory aux tank with any breather tube. I always had to set the filler in just right and dribble it in at the slowest speed.
 

nvrstuk

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Oh the days of filling my aux tank on my '68. My Dad's '69 was worse but upside down with the hose, filler gas nozzle only in about 2.675" or it wouldn't work at a slow trickle... LOL (wasn't funny then tho)... :)
 

thegreatjustino

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I never owned a factory aux tank with any breather tube.

I don't know what year the change was made, but the earlier auxiliary tanks had no vent tube, while the later ones had not only the vent tube, but the evap line that went to the accumulator behind the driver seat. I don't know if there's a version with vent but no evap, but all the ones with the vent I've seen have the evap port as well.
 

DirtDonk

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I think that's the case. Pretty sure that the changeover in '70 model year tanks is when the fill vent got added too.

Paul
 
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mimmonen

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Thanks for the input. I will give it another try with minimal insertion and just a dribble LOL. I did have the nozzle in too far probably blocking the air return. The fuel filler neck I removed did not have the vent tube. The new one did.
 

nvrstuk

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Just a Bronco driver for over 50 yrs!
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Well, here's a pic of my '68 aux tank with a vent on it.
 

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DirtDonk

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Good to know. Probably seen them before and just forgot. But for sure the change to EVAP and different filler neck/cap design happened on or around the '70 year.

Paul
 

DirtDonk

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Interesting thing about yours though. Is that the fitting for the emissions vent at the top? Plugged with some kind of contraption?
Did you do that or was it like that when you got it.

Paul
 

Speedrdr

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Nov 27, 2017
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I don't remember whether the '72 I used to own had a vent tube on the aux tank, but it always took seven forevers to fill that dinky tank. I hated filling it so bad that it was only used if I ran out of fuel in the main and HAD to use the auxiliary tank. Kept Stabil in the truck and put a scooch in to keep fuel from going bad.
Randy
 

No Hay

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Yep, post #2 and #3 for me also.

Not all stations pumps flow at the same slow speed either. I only use Chevron and the two stations nearest me flow at very different speeds, so the Bronco can only get filled at one station.

It finally hit me when watching it fill very fast into a gas can for the dirt bike.
 

DirtDonk

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I will give it another try with minimal insertion and just a dribble LOL.

I guess we should clarify though, that while your problem is an unfortunately all too common one, it's still not right.
You should be able to fill your Bronco like a normal human being without having to resort to trickery.
Well, I say "normal" but that would indicate you could just stick the nozzle in, set it and walk away. But that ain't gonna happen!

You should however be able to stick it most of the way in, pull back on the boot and fill the tank fairly quickly.
So yes, you still have something wrong. What it is, we don't know yet.

My '71 did it from the day I bought it (both tanks) until the day, several years later, that I changed the hoses and blew out the vent lines. No rhyme or reason to it, but it worked just fine after that.
It continued to work just fine when I installed my 23 gallon tank too.

My '68 is back to the old tricks though, and with this 23 gallon setup I can just barely dribble it in. And even still, it will back up and flood out of the filler neck when I'm not watching. Very frustrating to see the old telltale reverse-V shaped dribble permanently marking it's place in my new paint.
If you're older and noticed that kind of thing, that mark in the paint was an extremely common fixture of old cars and trucks. Especially trucks. I used to think it was just careless people because all of our cars always filled easily and even if something spilled, all of our cars just happened to have hidden caps so no paint damage was possible. Guess my dad was smarter than I thought!

After buying my first Bronco I realized that they weren't all careless after all!
Ya just gotta' walk in their shoes for awhile...;)

Paul
 
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mimmonen

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Mar 15, 2014
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My tank was completely empty when I tried to fill it. I did fill it once successfully. I am going to check and make sure the vent tube isn't blocked. Maybe cool fuel and a hot tank caused some kind of vapor lock. The day to day challenges of these Bronco's is why I love them.
 
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mimmonen

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Problem solved!! Vent hose was kinked. Tank must have moved after I installed it.
 

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sprdv1

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Yep, post #2 and #3 for me also.

Not all stations pumps flow at the same slow speed either. I only use Chevron and the two stations nearest me flow at very different speeds, so the Bronco can only get filled at one station.

It finally hit me when watching it fill very fast into a gas can for the dirt bike.

lol... dang filler hose, etc get silly sometimes don't they
 

jmhend

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Dec 25, 2007
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Problem solved!! Vent hose was kinked. Tank must have moved after I installed it.
Super late here and glad you found your problem.

After days of searching this is the best one that explained my question.

As “thegreatjustino” said the evap line that went to the accumulator behind the driver seat. In post #14 I see you have this port capped , are there pros or cons in plugging the Evapo port? I don’t have the accumulator behind the drivers seat (does anyone even make hard lines or kits fit these anymore)?

Happy to move my question to another thred if that helps too.
 
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