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Thread: Modified FFR fuel filler hose with vent added

  1. #1
    Senior Member beeman's Avatar
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    Modified FFR fuel filler hose with vent added

    I am going to go with a driver's side only fuel filler, but only could find a passenger side fuel filler tube in the shop. Rather than order a new driver side filler, which I couldn't find online, I figured I would just cut the passenger filler tube and rotate it to fit the driver side with a piece of 2" exhaust as a coupler. As soon as I did this, I realized that I should add a filler vent to vent the tops of the fuel tanks back to the filler. This keeps it a sealed system unless the filler cap is removed for filling and allows ventilation of the tanks during filling to speed up the filling rate. Anything else I should think of? Will still have a small tank vent in the system.

    Cut some tubing from a wiper arm. Tapered the end for welding, hole drilled in the exhaust tubing.



    Welded it up



    Probably overkill but took 30 seconds and added beads



    Not sure how well the original tube lines up, but the extra length and control of rotation makes this perfect.



    Last edited by beeman; 07-20-2019 at 10:28 AM.
    MK3.1 2004 Mach 1 donor. ABS, PS, TC.
    GTM #304 LPE 525hp LS3
    2000 C5 Lingenfelter LS1@489hp
    1999 Corvette FRC/Z06 track car

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    I really enjoy seeing all the great work and ideas you come up with. I’m sure I’ll incorporate something similar to this on my GTM.

    Question. Are you only going to vent the tops of your tanks to this filler tube location or are you also have a separate fuel tank vent filter?

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    Senior Member beeman's Avatar
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    As Shane reminded me, you always need a small amount of venting so that the fuel pump isn't creating a vacuum in the tanks as fuel is pulled out, so I will do a very small small carbon filter. I think the problem arises when you try to vent a tank through the restrictive carbon filter while fueling up. If you look at the OEM C5 fuel filler neck, it has a similar fitting as I have created that only vents when the fuel cap is removed for fueling, much larger hose than the carbon filter.
    Last edited by beeman; 07-24-2019 at 12:34 PM.
    MK3.1 2004 Mach 1 donor. ABS, PS, TC.
    GTM #304 LPE 525hp LS3
    2000 C5 Lingenfelter LS1@489hp
    1999 Corvette FRC/Z06 track car

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    Excellent, thank you for the clarification on the fuel system. That makes perfect sense.

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    Quote Originally Posted by beeman View Post
    As Shane reminded me, you always need a small amount of venting so that the fuel pump isn't creating a vacuum in the tanks as fuel is pulled out, so I will do a very small small carbon filter. I think the problem arises when you try to vent a tank through the restrictive carbon filter while fueling up. If you look at the OEM C5 fuel filler neck, it has a similar fitting as I have created that only vents when the fuel cap is removed for fueling, much larger hose than the carbon filter.
    OEM caps are usually venting caps. Point being that we are changing the system when we use the non vented FFR supplied filler caps. OEM does not require any vent other than the cap when the system is closed, and needs a higher volume vent only when the tank is being filled.

    Not to be a downer, but I don't see what good your "vent" is going to do? The vent is usually a separate line that comes from the top of the tank and goes up the side of the filler hose and re-enters the filler hose at where the fuel pump nozzle would be inserted. This allows the tank to vent when it is being filled with fuel, and also meets the requirements for fume capture, that many states mandate, by the filler nozzle. Where you have put your "vent line" in the middle of the filler hose really doesn't accomplish what is done on an OEM setup. Don't really know what your setup will help, or hurt, but it doesn't do what is needed for venting the tank during filling.
    Last edited by crash; 07-24-2019 at 02:17 PM.
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    Senior Member beeman's Avatar
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    Mike,
    I dealt with slow fill speeds at the gas pump with my Cobra for about a year until I added something similar. It took 10 minutes to fill up, had to trickle the fuel in, wait 10 seconds, etc.
    The nipple I welded on will have a section of fuel line leading to a Y to the tops of both tanks. Pretty much like OEM setups...I think that the location would be ideally proximal to the tip of the inserted filler nozzle, but I think that's a moot point.



    When refueling at full fuel flow, I can't imagine that the filler to will be more than 1/3 full with the fuel in the bottom 1/3. The upper 2/3 of the tube will be full of air that will vent through the open gas cap. The only reason this would not work as if I had a complete seal around the filler nozzle that would prevent air escape.
    Last edited by beeman; 07-24-2019 at 03:00 PM.
    MK3.1 2004 Mach 1 donor. ABS, PS, TC.
    GTM #304 LPE 525hp LS3
    2000 C5 Lingenfelter LS1@489hp
    1999 Corvette FRC/Z06 track car

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    Senior Member beeman's Avatar
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    Now that Mike has me thinking about this more, the GTM driver side tank would likely vent fine directly from the filler hose, but the opposite side tank would not.
    I will only be running a driver's side filler, so those of you with both side fillers could potentially accomplish the same thing by opening the passenger side gas cap.

    Is slow filling an issue for the GTM??? I thought it was...
    MK3.1 2004 Mach 1 donor. ABS, PS, TC.
    GTM #304 LPE 525hp LS3
    2000 C5 Lingenfelter LS1@489hp
    1999 Corvette FRC/Z06 track car

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    Quote Originally Posted by beeman View Post
    Now that Mike has me thinking about this more, the GTM driver side tank would likely vent fine directly from the filler hose, but the opposite side tank would not.
    I will only be running a driver's side filler, so those of you with both side fillers could potentially accomplish the same thing by opening the passenger side gas cap.

    Is slow filling an issue for the GTM??? I thought it was...
    It definitely is.

    What I was getting at was the fact that what FFR has in this kit is really nothing like an OEM setup, and as such there needs to be consideration as to what the OEM setup was doing and then a careful fix come up with if one wants to replicate OEM form and function.

    On the PDG GTM we simply vent to outside air with a separate house. I believe it is 1/2 inch on each tank.

    On my new car the design calls for one tank with two fillers. Thereby the car can be filled from either side, but it is only going into one tank. Thus when fuel is coming into one filler, then the other side filler can be used as a high volume vent. The idea is to dump a 5 gallon can into one side, and then the side with the pit wall will have a fueling tower that dumps the rest of a full 40 gallon fuel load into the car. Once it comes up into the 5 gallon can the cars tank is 100% full and both fueling couplers can be removed. I am using vented dry breaks.
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    VRaptor SpeedWorks, LLC's Avatar
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    Quote Originally Posted by beeman View Post

    Is slow filling an issue for the GTM??? I thought it was...
    Sort of....but I don't see it being related to venting. It has much more to do with geometry. If you stick the nozzle into the filler cap and have the nozzle pointing straight down, the fuel is hitting that rubber filler hose at a 90 degree angle and the fuel basically bounces off the bottom and sprays right back at you. Think of cutting a section of PVC pipe in half lengthwise and spraying a garden hose right at it. You're going to get soaked. There are a couple of solutions.

    1. Don't put the nozzle very far down into the filler neck and aim the nozzle slightly toward the rear of the car. The fuel hits the back side of the filler neck and the corner of the rubber filler hose shoots the fuel forward toward the tank.

    2. What works best for me is to stuff the nozzle down into the filler neck as far as you can get it and twist it so it's shooting the fuel toward the front of the car. That keeps it from bouncing off the bottom of the filler tube and directs it right toward the tank.
    Shane Vacek
    VRaptor SpeedWorks, LLC
    www.vraptorspeedworks.com
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