Went to fill up and noticed it was "boiling over" again. I've already replaced my filler neck once. Now what is it? How would I go about cleaning my filler neck vent.

 

Make sure the vent hose in the filler hose is not kinked and is not more than an inch or so in the tank.

 

Ok I'll tear into it and look at it.

 

Upon further inspection. I removed the filler neck. And there was a 1" diameter black rubber hose attached to the inlet side and cut off flush with the outlet side. No vent neck. Where could it have gone? Usually the ones I've seem are a small 1/4" hose for a vent.

 

The filler necks schemes seem to vary from what i've seen.

On my 85 F-250 there was a 3/4" or smaller plastic tube running inside the hose that fit into a place holder at the top of the fuel tank.

Can't remember the exact details but on my 90 E-150 there was an anti siphon float ball built into the filler neck.

Just pulled the tanks on my 94 a few weeks ago and it's altogether different. The plastic / rubber tube that runs inside is the fuel filler and runs all the way into the tank. It seems like it's all reversed and the large rubber hose on the outside is now the vent hose ?

I guess you have to think it through to figure out how it's supposed to work in your particular situation. What holds true for one might not for another.

 

The small hose should not be in the tank, it probably slipped down, the purpose of the small hose is to release the air from the top of the tank as the gas is filling the tank, and if the end of the hose is submerged in gas in the tank, the gas going into the tank will counter act with the air trying to escape through the filler hose, thus creating the boiling over situation.

 

Ok. I'll see if I can figure out where it went tomorrow.

 

I found out a while ago when I got my first truck how important that vent hose is.

 

If I can't find it is there a way I can rig one up?

 

Not necessarily.

I pulled the bed to get at the tanks on my 94 a couple of weeks ago. With the bed out of the way everything is right there in front of you.

I dropped both tanks & opened everything up to get a good take on the overall condition of things. The rear tank was a lost cause so i just capped the lines going back there and left it out.

The filler neck assy on both tanks is the same. I've got the rear filler neck assy sitting on the desk right next to me.

The inside plastic tube is about 1 1/8" OD. It extends 5" past the outer hose which is about 2 1/4" OD.

The plastic tube is the filler and is meant to extend 5" into the tank.

It's the same on both tanks and that's the way it was intended to be.

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It may be that a 92 shortbed is set up different. Could be that they're the same.

Here's the thing.... a week before doing anything with the fuel tanks i unscrewed the three 7 mm screws & two hose clamps holding the filler neck assy on the midship tank & pulled it.

It was getting rusty so i wanted to give it a coat of primer and a couple of coats of paint before it rusted through.

When i went to reinstall it that plastic tube would not feed back down through the outer rubber hose and down into the tank.

That's why i pulled the bed ... so i could get a better take on what was happening.

Long story short ... it's a PITA to reinstall a filler neck with everything in place. It has to be twisted and turned in a very specific way in order to get it to feed back down in again.

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If i had to guess on welder's problem there is one of two possibilities.

1: The guy before him ran into the same problem and instead of doing it right he cut the plastic filler tube off flush with the outer rubber hose so that it would go back together.

2: If he's going to the same pump and the same station every time it might not be a problem with his truck at all.

Sometimes the automatic shutoffs on the pump wear out and it's awhile before the station owner figures out that there's a problem & fixes it.

Who knows though ... you can't assume. A 94 longbed setup might be completely different than a 92 shortbed.