Fuel filler issue

Viktor Kovacs

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Hi guys,

I really need some help here. I bought a 74 stepside, the PO put an 85 cab and bed on it.

So the problem I have is that I have a 74 fuel tank, but an 85 fuel door and filler. The geometry of this is kinda weird. The PO just patched together a solution (see attached pics). This creates an "S" shape. When you go to fill up, the fuel pools and backs up and you end up spilling every time.

So I bought some proper fuel filler hose and ran it. I don't have pics of this but it fit. However, it still tends to back up and spill. Has anyone ran into this issue?

What's the proper solution here?

Get an 80s tank? Will that fit without modification?
 

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Bextreme04

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It doesn't look like you need anything new. It looks like everything is just too long and is creating a down loop that is letting the breather air lock. I would suggest turning the elbow on the tank to face more outboard or go get a 45 degree instead of a 90 degree elbow. Then shorten the fill tube where it goes into the filler so it doesn't drop as much. That way it is a constant downhill feed into the tank. The breather hose needs to be shortened to get rid of the down loop as well.
 

Viktor Kovacs

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It doesn't look like you need anything new. It looks like everything is just too long and is creating a down loop that is letting the breather air lock. I would suggest turning the elbow on the tank to face more outboard or go get a 45 degree instead of a 90 degree elbow. Then shorten the fill tube where it goes into the filler so it doesn't drop as much. That way it is a constant downhill feed into the tank. The breather hose needs to be shortened to get rid of the down loop as well.
Thanks for your response. Like I said I took that copper fitting and rubber couplings off and put on a proper fuel hose. I made sure that's not 1 cm longer than it needs to be. There the slightest of down loop on it, but very little. I didn't touch the breather. I didn't think of that, so I'll give it a shot. Why would that affect it?
 

Bextreme04

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Thanks for your response. Like I said I took that copper fitting and rubber couplings off and put on a proper fuel hose. I made sure that's not 1 cm longer than it needs to be. There the slightest of down loop on it, but very little. I didn't touch the breather. I didn't think of that, so I'll give it a shot. Why would that affect it?
That hose is what lets the air out of the tank that you are displacing with the fuel going in. The pump will automatically click off when the fuel gets high enough to reach that breather line and shoots fuel up it. If you have a big dip in the hose, fuel could get in there while you are driving around, or stay in there from the last time you filled it, and plug the breather. If that breather is plugged, then the only way for the air to get out of the tank as you fill it is by coming back out the same tube you are putting fuel into, which obviously will not accommodate high speed filling and will cause it to back up and spill out.
 

AuroraGirl

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This is my 1980 filler neck on the side of a bed with no doo. but the neck and the hoses are right, do you need the metal part that screws into the opening of the door? you probably can make it work, its just a basic flange thing
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Heres the other side which has a bad neck and tank. But you can see what i mean by screw. the later 80s bed doors has a more filled opening i think but you could prob still fit it.
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Viktor Kovacs

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So here is my setup, you can see it's pretty damn direct. I cut the breather tube as short as possible and tightened the clamps until I couldn't anymore. It seems to have stopped leaking. BUT at the gas station, I can't hold the trigger all the way down, full pressure. The fuel will come back out the filler hole. However, if I just feather trigger it seems to work fine. Not sure what I can do.
 

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AuroraGirl

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my bad, you have a stepside i didnt see that. whoops.
@C10MixMaster provided these examples of his truck. do you have the 76-78 height, which is high compared to the earlier low fill, or do you have a door?
 

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AuroraGirl

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if you haave a low fill tank you are unfortunately limited by the technology of your beds fender cutout design. there is no way around the original diameter hose and neck and fill issues without a steeper fill angle or just less flow from nozzle. may be able to fix the kink/bind if thats happening but let us know
 

AuroraGirl

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i think you have a 1979 ish + stepside bed with a driver side fuel door, yes? if so, you look like


your gas pipe appears to be for.. a gaser? It almost looks like the passenger side on the driver side, which also is angled down..?
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and that run there thats flat is whats killing you. the neck is fatter than the hose, which is normal, but the whats happening is the fuel is slowing down a lot even with unleaded restrictor your pipe definitely has and your vent hose is not a vent hose(wtf is it) and its clearly making a collapse where the big one is turning too, so its either vapor checking or your fuel hose running parralel to the ground for half the reach is causing it to flow up thhe neck and probably over into the vent, which would be a whole lot of science i cant explain but math, physics, hippies, and probably PETA would have words lo.

What neck did you buy, what year is your bed, you didnt modify anything right your tank looks right, 16 gallon swb tank
 

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Viktor Kovacs

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i think you have a 1979 ish + stepside bed with a driver side fuel door, yes? if so, you look like


your gas pipe appears to be for.. a gaser? It almost looks like the passenger side on the driver side, which also is angled down..?
You must be registered for see images attach

and that run there thats flat is whats killing you. the neck is fatter than the hose, which is normal, but the whats happening is the fuel is slowing down a lot even with unleaded restrictor your pipe definitely has and your vent hose is not a vent hose(wtf is it) and its clearly making a collapse where the big one is turning too, so its either vapor checking or your fuel hose running parralel to the ground for half the reach is causing it to flow up thhe neck and probably over into the vent, which would be a whole lot of science i cant explain but math, physics, hippies, and probably PETA would have words lo.

What neck did you buy, what year is your bed, you didnt modify anything right your tank looks right, 16 gallon swb tank
Well like I said in the original post, it's a 1974 stepside, but the body and cab were swapped to a 1985 by the PO, so it has the square fuel door.

As far as the filler neck, I don't know if the PO kept the 74, used the 85, or something else entirely.

I would love to get rid of that flat spot, but ultimately it's not physically possible. That fuel hose is absolutely as short as it can be.
 

AuroraGirl

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I think one of these and a hose setup like the
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idk, I think the neck your bed is using is incorrect or its position wrong. It just doesnt seem right. Can you show us the other side from the fuel door
 

Viktor Kovacs

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I think one of these and a hose setup like the
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idk, I think the neck your bed is using is incorrect or its position wrong. It just doesnt seem right. Can you show us the other side from the fuel door
The filler neck you posted wouldn't work because it's too fat at 2" in diameter. I am currently looking into some universal filler neck applications.
 

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AuroraGirl

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The filler neck you posted wouldn't work because it's too fat at 2" in diameter. I am currently looking into some universal filler neck applications.
you could expand that with a hole sawor just cut it out larger with various means. but that is a nice pic, that helps. you have an older style neck with a different fender then. that means its probably the pre 76 neck with a different height on the fender of a 80s fender.your neck is angled a lot different than it was intended to be used. So you would probably gain from getting a

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looking at all of it, I think you want #2 in the first two, which appears the same, which is for the fuel doors with a plastic case, then you need the right hose. the problem is finding the right hose sucks, but i think you have the old gas tank. Which isnt going to play well together, but you can make it play well or change tanks or fab up a mount or try clocking the one you have

I Think the filler neck is just wrong, like its not for that tho
 

AuroraGirl

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I apparently have one of the last ones, which is what i think is like yours but you have a short one essentially. i think.. confusing stuff lol.
 

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