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  • Sump vent question

    I'm using the Edelbrock Sump fuel pump for my E-Street EFI. Can you think of any reason I can't use a motorcycle crankcase breather/filter connected directly to the sump vent fitting? It's has a filter element much like a K & N air filter and is about 2'' in dia and about 1 1/2" long and has a tube that's 3/8" OD that will clamp directly to the 3/8" ID vent hose. I can run the vent hose down away from the sump and connect the breather to the end.

  • #2
    You need to have a "place" to contain the gasoline that comes out of the vent. When the floats in the sump get stuck in the open position.
    The only "place" to do these at. Is the fuel tank.

    Most vehicles since the 70's have 1 or 2 lines going back to the fuel tank that can be used for this purpose.
    Ether the fuel return line ( if the engine mounted pump was using the return line. Replace it with a pump that does not use a return line. )
    Or. Use the fuel "vapor" line that goes to the charcoal canister "from" the fuel tank. The canister is not needed for a none smog installation.

    Every gas tank has to have a "vent". This is where the vent of the sump should go.

    If the fuel tank uses a " vented fuel cap" only. There's only 3 options that I know of.
    1. Install a vent "fitting" on the tank or sending unit.
    2. If the fuel tank sending unit uses 5 small bolts to hold it in. It can be replaced with a "diesel" unit. As these always have a "return" fitting.
    3. If the fuel fill neck is connected to the tank by a hose. There are kits that replace part of the hose with a pipe that has a return fitting on it.

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    • #3
      Good point. I didn't consider the possibility of the float sticking open. The car doesn't have a canister or a return line but the gas tank does have a vent so I'll go that route.

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      • #4


        We were discussing this on another website. A user with a 72 Challenger pulled his charcoal canister and hooked that feed line to the vent line on top of the sump. His car died one day and the white plug had popped out. He sent the sump to Edelbrock for inspection, they repaired it, then sent it back. Driving to Columbus, Ohio in August, the car dies again, plastic plug popped out, car dies. I put a strap on it as shown in the picture, which got him home.
        Thinking about it later, I figured it out. He filled up the tank, got stuck in traffic, the fuel expanded, went to the sump then popped out the plastic connector, car dies. He had plugged up the vent line meant for fuel/vapor expansion, forcing it into the sump.
        I told him to put a filler neck in from a 70 Challenger, that has a top mounted vent line, running to the outside of the car, or put the canister back in and run another return line. His fuel was expanding with no other place to go but the sump. Kept calling Edelbrock and complaining. Everyone always blames the fuel injection first before troubleshooting logically.

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        • #5
          I have an '82 C10 pickup w 350, I have the E-Street V2 kit with Sump and I'm in process of hooking up my vapor canister. I have the 5/16" vent tube back to tank and T to vapor canister. My questions is: Can I connect vapor canister Carb bowl port with T into 3/8" PCV line that goes from 3/8" PCV port on throttle body to PCV in rocker cover? I know it says not for fuel on the throttle body 3/8" PCV port, so that's why I'm asking. If not, how would you recommend? Thank you!

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          • #6
            As stated above, the vent line must return to the tank. There is vapor that vents out of the sump and in the case of a float sticking open due to debris, then liquid fuel can come out. The only safe place is the tank and make sure that the tank is properly vented.

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            • #7
              Originally posted by SugarBearJr View Post
              I have an '82 C10 pickup w 350, I have the E-Street V2 kit with Sump and I'm in process of hooking up my vapor canister. I have the 5/16" vent tube back to tank and T to vapor canister. My questions is: Can I connect vapor canister Carb bowl port with T into 3/8" PCV line that goes from 3/8" PCV port on throttle body to PCV in rocker cover? I know it says not for fuel on the throttle body 3/8" PCV port, so that's why I'm asking. If not, how would you recommend? Thank you!
              You would not want to tee your vapor canister into the sump vent line. The sump vent is a "wet" vent and needs to go to the gas tank and only the gas tank. Unless you want to fill your vapor canister full of gas, you should absolutely not have it tied into the sump vent. A vapor canister is for dry venting only and is only meant to capture vapors. A vapor canister normally pulls from the highest practical point on the fuel system to get only vapor and not actual liquid gas.

              You need to change your setup immediately.

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              • #8
                Thanks for your prompt reply. Maybe I didn't explain my setup. I'll try again. I have the sump vent tube going down to a T into a hard line that runs to the tank, and the other end of the vent hard line runs over and up to the tank port on the vapor canister. If I understand your instruction, the vent port on the sump and the line going to the tank would all have to be downhill to the tank to drain fuel. This would be difficult for most users to achieve. I'm almost certain my sump vent is currently at same height as tank, but the lines between go down & up again, prob. would not drain. Is there any other option?

                I didn't realize I may be doing the sump vent wrong, but my real question was can I T in the carb bowl port (separate port than vent) on the vapor canister to the PCV port on throttle body?

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                • #9
                  I completely understand what you did and you shouldn't do it that way. The orientation of sump height to tank height and uphill or downhill has no relevance. The vent is pressurized. It will push liquid fuel out of it and push it all the way back to your fuel tank. Because of this, you absolutely would not want to have a vapor canister on this same vent line as the sump vent will most likely fill it full of gas. The right way to do it is to have a dedicated vent line from the sump to the tank and a dedicated line from the tank to the vapor canister. Regardless of the height of the vapor canister, it always pulls from the highest point on the fuel tank or higher (like up on the filler tube).

                  A modern car has purge solenoid that's controlled by an ECU that opens the solenoid when necessary (and only for a very short period of time) to vent the fuel system and have the vapors consumed by the engine. Since you do not have an ECU controlled purge solenoid, you would not want to have the fuel tank vent subject to constant vacuum. In cases where you don't have a purge solenoid, you typically vent the vapor canister to the engine's intake ahead of the throttle body so the vapors do get consumed by the engine but the system is under constant vacuum.

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                  • #10
                    OK roger that I will fix the sump vent. Thanks for explaining the pressured sump vent, I don't think I read any of that in the instructions,except that it must be connected. Kinda strange the sump exclusively occupies the tank vent line and then you have to run a separate line to use the charcoal canister. This was not explained well in the instructions. Do most people just use vented cap & no canister with this setup?

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                    • #11
                      The instructions don't go into specific details on why but the important point is made clear - the sump should be vented back to the tank. Also, the sump vent would not be plumbed into the tank vent. The sump vent is for pressure out of the sump and the tank vent is also for pressure out from the tank. You wouldn't want the two pressures working against each other. The sump should have its own vent line and the tank should also have its own vent line. All Edelbrock EFI systems are for pre-emissions or offroad vehicles so no, vapor canisters aren't commonly used. Plumbing one in does add in another layer of complexity. Just treat each component as its own separate part of the system and address each one individually.

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                      • #12
                        Just a suggestion but Edelbrock should put in the sump instructions the vent is actually a pressurized purge port. When I read "vent" I think of fumes, not liquid fuel. I have a return line port on my tank, but now have to add another line. It would have been helpful to have the instructions say tap into your return line to tank, not vent line.

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                        • #13
                          I do appreciate the help, I'm just cranky I have to add another line.

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                          • #14
                            OK, I got home and reread the instructions and it says:

                            "The fuel sump vent line is a critical part of the Fuel Sump installation. These instructions MUST be followed for safe and proper system operation. A fuel rated hose must be routed from the vent port (see figure #4) back to the fuel tank. The fuel tank must also be vented if not originally equipped with a vent line or vented cap. If the vehicle has a vent line, you can tee into this line. If no existing vent line to the fuel tank exists, you must plumb a new line to a point above the maximum fuel level of the tank (at the top) or in the fill neck. DO NOT run a vent line from the Fuel Sump to OPEN AIR in the engine compartment or pointed to the ground. DO NOT run the vent line into any part of the air intake system. Proper routing of the vent line is not an option. This procedure is mandatory for your safety. Edelbrock is not responsible for any fires, personal injuries, property damage or any other issues pertaining to improper vent line routing and or failure to follow these instructions."

                            This is where I got the idea to T into my vent line.

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                            • #15
                              See step #11 from the instructions. It says if vapor canister has been removed, the existing hard line is good to use for vent line to tank. I'd be careful tee'ing into a existing vent line. This gives the vapor and possibly liquid gas a possible alternate path that doesn't end up at the tank. It all depends on how you go about doing it.

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