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Filler neck question

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Old Sep 17, 2010 | 03:05 AM
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Default Filler neck question

I'm finishing up my work truck swap and I have a question. Since I'm using a Tahoe/Blazer tank that mounts where the spare tire usually goes I have to fab up a custom filler neck. I think the filler neck that I'm making will work but I'm pretty nervous that It won't for some reason. What do you all think?

I don't have a pipe bender so I have to angle cut then weld up. Doing it this way is probably better since there needs to be some pretty sharp turns.











Here is a picture of the side of the truck to give you an idea of how much higher the filler is compared to the frame. I know the back of my cab is sagging pretty low, I don't have the rear cab mounts welded onto the frame yet.



So, what do you guys think?
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Old Sep 17, 2010 | 06:45 AM
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The body on the truck looks clean. Are you gonna detail the frame once complete?
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Old Sep 17, 2010 | 08:42 AM
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I don't think it's going to work properly, especially if you're planning on using the stock filler opening on the side of the bed. Gas isn't going to flow uphill over the frame rail to enter the tank properly and the long, straight run of the filler tube along the frame will stay full of gas blocking air trying to escape the tank as it's being filled. I'll give you thumbs up on the fab work but the design theory is seriously flawed. The gas filler needs to be a fairly straight, downward entry into the tank. If you absolutely have to use this tank set-up, you should consider a filler opening in the floor of the bed located right above the tank opening, street rodders having been doing it that way for decades. JMO

Mike
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Old Sep 17, 2010 | 09:02 AM
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the fabbed up filler kneck will at like a "p trap" in a sink. you will alway have fuel in the section of pipe before the fabbed elbow going over the frame.
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Old Sep 17, 2010 | 09:03 AM
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ok. I should of fully read the previos post before mine. He stated the same LOL
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Old Sep 17, 2010 | 09:38 AM
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if anything, keep the bottom of the fill pipe even with the top of the frame rail that way it doesn't act like a trap like the previous two said.
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Old Sep 17, 2010 | 12:05 PM
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Can you cut a hole int he frame to pass the filler tube through so it's a straighter shot into the tank.?
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Old Sep 18, 2010 | 10:07 AM
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Looks like you are not afraid of welding. I suggest you remove the filler assembly from the stock location including the bump in the bed, and move it behind the wheel. Straight shot, no 'P' trap, will look factory.
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Old Sep 19, 2010 | 08:17 AM
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Originally Posted by Jimbo1367
The body on the truck looks clean. Are you gonna detail the frame once complete?
HA! The truck doesn't have any major dents or scratches but don't let that fool you! It's my work truck/daily driver and now it's a sleeper! The ugly frame stays!!!

Originally Posted by Mike52
Gas isn't going to flow uphill over the frame rail to enter the tank properly and the long, straight run of the filler tube along the frame will stay full of gas blocking air trying to escape the tank as it's being filled. I'll give you thumbs up on the fab work but the design theory is seriously flawed.
The air in the tank doesn't exit out the filler neck, it exits out the breather on the top of the tank. It's the fat rubber hose on the pump/sender unit in this picture.

Originally Posted by xXxSilveradoxXx
I would think that it would work about the same as the "P-Trap" that the other's have said. As long as the filler on the side of the bed was higher than the highest part of the piping it would still flow regardless. Something like this.



Originally Posted by Jimbo1367
the fabbed up filler kneck will act like a "p trap" in a sink. you will alway have fuel in the section of pipe before the fabbed elbow going over the frame.
I wouldn't mind having fuel in there the whole time, as long as it would flow when needed.

Originally Posted by claytonisbob
Can you cut a hole int he frame to pass the filler tube through so it's a straighter shot into the tank.?
I can't cut a hole in the frame since the rear leaf-spring mount is right there. Plus, the inlet is too high and is at about a 45° angle.

I have, however, re-designed it for what I think will be much better use. Although it will be initially a bit harder to make. Here is the basic idea of it.



Basically there will be a 90° rubber hose coming out of the tank pointing to the front of the truck (on the inside of the frame) connected to a 2" pipe. Then, a 90° rubber hose straight to the stock filler. It will be a PITA to notch 2 more under bed crossmembers but I think it will be worth it.
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