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Universal 6AN Fuel Tank Return Line Collapsible Bung Kit (9/16"-18 Thread / Drill-In No-Weld Installation / Billet Aluminum)

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$35.99 $39.38 Save $3.39
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  • Not sure? Email support@k2-industries.com for a real specialist to help you order
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K2 Industries  |  SKU: 1005010712995577-China Mainland

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Details

Add a return line port to virtually any fuel tank without welding using this premium collapsible bung kit, precision CNC-machined from 6061-T6 aircraft-grade aluminum for permanent durability and reliable fuel system sealing. Adding a fuel return line to a tank is a common requirement for engine swap projects, EFI conversions on carbureted vehicles, fuel system upgrades, and dedicated race fuel cell installations — but traditional welding installation requires removing the fuel tank, draining residual fuel, and exposing the tank to welding heat near explosive fuel vapors. This collapsible bung kit eliminates the welding requirement entirely with an innovative drill-and-collapse installation that creates a secure, leak-free threaded fitting in just minutes. Simply drill a 1/2" hole, insert the collapsible bung, and tighten the center bolt — the bung collapses inside the tank, pressing against the interior tank wall to create a permanent sealed connection point. Includes a 9/16"-18 thread to 6AN fitting for direct integration with standard performance fuel system plumbing.

Features:
  • No-weld installation – allows you to add a threaded fuel line bung to virtually any fuel tank without welding, dramatically reducing safety risk and installation complexity
  • Simple drill-and-collapse design – drill a 1/2" hole, insert the bung, and tighten the center bolt to collapse the bung against the inside of the tank for permanent secure mounting
  • Premium 6061-T6 billet aluminum construction – CNC machined from aircraft-grade aluminum for exceptional strength and durability
  • Anodized surface finish – delivers superior rust resistance and corrosion protection against fuel exposure
  • O-ring included – prevents leakage and ensures fuel-tight sealing at the bung-to-tank interface
  • Compatible with tank wall thickness up to 1/4" – works with virtually any automotive fuel tank, fuel cell, or aftermarket tank
  • 9/16"-18 thread to 6AN fitting – direct compatibility with standard performance fuel system plumbing
  • Universal application – fits any fuel tank application requiring an additional return line port
Specifications:
  • Condition: 100% Brand New
  • Type: Universal Fuel Tank Return Line Collapsible Bung Kit
  • Material: 6061-T6 Aircraft-Grade Billet Aluminium
  • Construction: CNC Machined
  • Surface Finish: Anodized
  • Thread Size: 9/16"-18
  • Fitting Size: 6AN
  • Hole Size Required: 1/2"
  • Maximum Tank Wall Thickness: 1/4"
  • Sealing: O-Ring (Included)
  • Item Weight: 0.07 kg
  • Quantity: 1 complete bung kit per pack
  • Position: Fuel Tank Return Line Port
  • Purpose: Custom Fuel System Installation / EFI Conversion / Engine Swap Component
Fitment:
  • Universal application – compatible with virtually any automotive fuel tank, aftermarket fuel cell, or steel/aluminum tank requiring a return line port
  • Compatible with tank wall thickness up to 1/4" (6.35mm)
  • Suitable for engine swap projects, EFI conversions, carb-to-EFI upgrades, and dedicated race fuel system installations
  • Compatible with standard 6AN performance fuel line plumbing
Contents:
  • 1x Universal Fuel Tank Return Line Bung Kit (Collapsible Bung + 9/16"-18 to 6AN Fitting + O-Ring + Mounting Hardware)
Benefits:
  • Eliminates the welding requirement traditionally needed to add fuel tank ports – significantly safer than welding near fuel vapors and dramatically simpler installation
  • Enables EFI conversion on carbureted vehicles – many EFI systems require a return line, and this kit provides a clean way to add the return port to existing tanks
  • Critical component for engine swap projects – allows the addition of return-style fuel systems to vehicles originally equipped with return-less or carbureted fuel systems
  • 6061-T6 aircraft-grade billet aluminum construction provides permanent dimensional stability – will not corrode, crack, or fail when properly installed
  • Anodized finish protects against fuel exposure, weather, and underbody conditions for the lifetime of the installation
  • O-ring sealing ensures permanent leak-free operation – critical for fuel system safety and avoiding costly fuel leak issues
  • Compact design enables installation in tight tank locations where welding would be impractical or impossible
  • Universal compatibility makes this versatile for any fuel system project across virtually any vehicle platform
  • Significant cost and time savings compared to professional welded bung installation – this kit can be installed in minutes by any DIY builder
Important Use-Case Notes:
  • Universal application: This bung kit works with virtually any fuel tank, but installation location should be carefully selected to ensure proper return line submersion and tank function
  • Tank wall thickness limit: Compatible with tanks up to 1/4" wall thickness – verify your tank wall thickness before ordering
  • Tank material compatibility: Works with steel, aluminum, and most plastic fuel tanks – verify compatibility with your specific tank material
  • Required tools: Installation requires a 1/2" drill bit, drill, and torque wrench or power tool capable of 60 Nm torque
Installation Notes:
  • Safety first: Drain the fuel tank completely or remove residual fuel before drilling – fuel vapors are explosive and any sparks during drilling can cause catastrophic ignition
  • Proper safety equipment: Use eye protection, work in a well-ventilated area, and have appropriate fire suppression equipment readily available during installation
  • Tank position selection: Choose the bung location carefully – the return line outlet should be positioned to ensure proper return line submersion under typical fuel levels and to avoid interference with the tank's fuel pickup or sending unit
  • Mark and drill a 1/2" hole at the selected installation location – use a step bit or precise hole saw for clean cutting
  • Deburr the hole edges thoroughly before installing the bung – sharp edges can damage the O-ring during installation
  • Insert the bung through the hole from outside the tank with the O-ring properly seated
  • Position the bung's collapse mechanism inside the tank – verify proper orientation before tightening
  • Tighten the center bolt to a torque value of 60 Nm using a torque wrench or power tool – this collapses the bung internally to create a sealed connection
  • Verify the bung is firmly seated and pressed against the inside tank wall after tightening – it should not rotate or move when tightening is complete
  • Connect 6AN fuel line to the threaded fitting using appropriate AN-grade fuel line, hose ends, and clamps
  • Test for leaks before refilling the tank with fuel – pressurize the tank with air or use a leak-down test method
  • Refill the tank only after verifying leak-free operation
  • Inspect the installation periodically for any signs of leakage or loosening
  • Professional installation strongly recommended for first-time installers or for installations on plastic fuel tanks
  • If unsure about installation procedure, tank compatibility, or safety considerations, consult a qualified fuel system specialist before proceeding
Warranty:
  • 12-month standard warranty from date of purchase
  • Contact our support team for assistance with any issues

Our Guarantee

Warranty Assurance:

At K2 Industries, your satisfaction is our priority, and we stand behind the quality of our products. Here's a brief overview of our warranty:

Defect Coverage:
If you find a defect after receiving your order, get in touch with us. We're committed to resolving the issue, whether it involves a replacement, repair, or refund.

Installation Note:
Please inspect your purchase before installation. Unfortunately, damages post-installation are not covered, so ensure everything looks good beforehand.

Claims Made Simple:
Need to make a claim? Reach out to us at support@k2-industries.com. We're here to assist you. Just keep your original packaging and documentation handy.

Your Satisfaction Matters:
Your trust in K2 Industries is appreciated. We're dedicated to ensuring your satisfaction with our quality automotive parts.

Shipping & Returns

Shipping Information:

At K2 Industries, we strive to provide a seamless and efficient shopping experience for automotive enthusiasts like you. Our commitment is to deliver high-quality parts to your doorstep with the utmost care.

Fast and Reliable Shipping:
Many of our products are stocked in our local warehouse, ensuring swift processing and delivery. Orders placed for these items typically ship within 2-5 business days, allowing you to get your parts in no time.

Extended Selection, Global Reach:
To offer you a broader range of automotive parts, some items are sourced from trusted suppliers around the world. While these products might have a slightly longer processing time, we assure you that the wait is worth it for the exceptional quality and value they bring.

Shipping Transparency:
For products shipped internationally, we provide estimated delivery times on the product page. Rest assured, we are continually working to optimize our supply chain and minimize any potential delays.

Combined Shipments:
To streamline your shopping experience, if your order includes items from both our local warehouse and international suppliers, they may be shipped separately. You will receive separate tracking information for each shipment.

Questions or Concerns?
If you have any questions about shipping or would like assistance tracking your order, our dedicated customer support team is here to help. Feel free to reach out to us at support@k2-industries.com.

You can also track your order here

Thank you for choosing K2 Industries for your automotive needs. We appreciate your trust in us.

FAQs

How do I confirm this part fits my vehicle?

Use the vehicle selector at the top of this page to verify fitment. If anything's unclear, send us your year/model/trim (or VIN) via live chat or email support@k2-industries.com — we'll confirm fitment for free, before you commit.

How long until I get my order?

In-stock items typically process in 3-5 business days, then ship — most domestic orders arrive within 3-7 business days after that. Larger freight items take 3-10 days in transit. Some items are made-to-order (carbon fiber, aero kits) and require 10-25 business days of production before shipping — these are marked on the product page.

What if it arrives damaged?

Inspect your shipment when it arrives, take photos of any damage to the box and part, and reach out via live chat or support@k2-industries.com. For freight deliveries, note visible damage on the paperwork before signing. We handle the carrier claim and get you a replacement.

What if I want to return it?

You have 30 days from delivery. As long as the part is uninstalled and in original condition, you can choose between an exchange, store credit (no fees, never expires — our most popular option), or a refund. Drop us a message and we'll walk you through the easiest path.

Can I install this myself, or do I need a shop?

Depends on the part. Some are straightforward DIY, others are body shop or specialist work. Each product page indicates the recommended install path. If you're unsure, message us with your build details and we'll give you a real assessment.

What's the fastest way to reach you?

Live chat and email — typical response time is a few business hours, and you can reach out anytime. Chat with us on the site or email support@k2-industries.com. We resolve issues directly far faster than going through your bank or card processor.

The K2 Difference

  • • Built by enthusiasts who've made every fitment mistake you're afraid of. Now we verify parts for 30,000+ builds a year with zero wrong-part claims.
  • • Real specialists answer your questions in minutes, not chatbots reading scripts. We've built the same cars you're building.
  • • Freight damage, wrong parts, installation question, we handle it so you don't deal with suppliers or shipping companies.
Founder photo

Built By Someone Who's Been There

Max, the Owner, started in his garage making E36 M3 tail lights in his own oven.

  • • Started modifying cars before he could legally drive them
  • • Spent years hunting down parts that actually fit and don't suck
  • • Made the same fitment mistakes you're afraid of

You’re not buying from a warehouse. You’re buying from someone who builds cars just like you do.

Founder photo

What You Get With Every Order

Products Selected to Meet Quality & Fitment Standards we Stand Behind.
Products Selected to Meet Quality & Fitment Standards we Stand Behind.
Get Help From People Who Actually Understand Builds & Fitment.
Get Help From People Who Actually Understand Builds & Fitment.
Designed to Resist UV Exposure, Wear, and Everyday Use.
Designed to Resist UV Exposure, Wear, and Everyday Use.
Join Thousands of Builders Who Trust K2
Join Thousands of Builders Who Trust K2

What Sets K2 Industries Apart?

We don’t just sell parts. We actually care.
Pre-Order Fitment Verification
Damage Replacement
Real Experts Answer the Phone
Post-Purchase Installation Support
Curated Quality
30-Day Returns
K2 Industries
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K2 Industries
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Pre-Order Fitment Verification
Damage Replacement
Real Experts Answer the Phone
Post-Purchase Installation Support
Curated Quality
30-Day Returns
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GuaranteePerfect fit guaranteed

Frequently Asked Questions

How do I know this will actually fit my car?

Every part listing shows compatible years, models, and trims. But here's the thing—trim packages and factory options can be confusing. If you're not 100% certain, text us at 772-277-2495 with your VIN or photos of your car. We'll verify fitment before you order so you're not stuck with an $800 part that doesn't fit. We've done this for 30,000+ builds. We've seen every weird trim combo and factory option. Takes us 2 minutes to verify, saves you weeks of headaches.

What if the part arrives damaged or is the wrong item?

We handle it. You don't fight with freight companies or file claims. Text us photos within 48 hours of delivery. If it's damaged or wrong, we ship a replacement immediately. You're not waiting 6 weeks for a freight claim to process. We eat the cost, not you. This is why we package everything like it's going to war. But if something slips through, we fix it ASAP. No forms, no back-and-forth, no "file a claim and wait." Just text us and we handle it.

Can I install this myself or do I need a shop?

Depends on the part. Emblems, front lips, some spoilers, bolt-on, DIY-friendly, you can do it in your driveway with basic tools. Full bumpers, hoods, wide-body kits, possible for experienced DIYers but most people take them to a shop for paint and install. Check the product description for installation difficulty. If you're unsure, text us. We'll be honest about whether you can handle it or if you should take it to a pro. We'd rather you know upfront than get frustrated halfway through.

What's your return policy if it doesn't fit or I don't like it?

30 days, unused parts in original packaging. You pay return shipping unless we sent the wrong part or it arrived defective. Once you install it, modify it, paint it, or mount it, we can't take it back. That's why we push so hard on verifying fitment BEFORE you order. We don't want you stuck with something you can't use. Text us before ordering if you're unsure. We'll confirm fitment so you never have to worry about returns.

Do you offer financing?

Yes. Affirm and Shop Pay available at checkout for orders over $50. Split payments over 3-12 months depending on order size. No hard credit check to see your options. Most people use this for big-ticket items like body kits, suspension setups, or wheel/tire packages. Rates vary based on credit. You see the monthly payment before you commit. Makes it easier to build now instead of waiting months to save up.

What if I have questions after I receive the part?

Text 772-277-2495. We don't disappear after you buy. Fitment questions, installation issues, "does this bolt go here" questions... we'll walk you through it. We've installed these parts ourselves or helped hundreds of people install them. You're not getting transferred to a call center in the Philippines. You're texting someone who's actually installed your part before. If we can't help remotely, we'll recommend a local shop that knows these parts.

Why should I buy from K2 instead of eBay/Amazon/other sites?

eBay and Amazon sellers don't answer fitment questions. They don't verify your VIN before shipping. They don't handle freight damage claims for you. If something goes wrong, you're filing disputes and waiting weeks. We're builders selling to builders. We verify fitment before you order. We handle damage claims same-day. We answer texts in minutes. We're not the cheapest, but you're not gambling $800 on whether a part fits. You're paying for support, verification, and someone who cares if your build goes sideways.

What does your warranty cover?

1 year against manufacturing defects: cracking, warping, paint peeling, hardware failure, fitment issues caused by the part being made wrong. Does NOT cover installation damage (you cracked it bolting it on), road damage (curb rash, rock chips), or normal wear. If it breaks because we made it wrong, we replace it free. If it breaks because you hit a parking block, that's on you. We're fair about it. Send photos and we'll tell you honestly if it's covered.

Shipping

Do you ship overseas?

Yes, we ship all over the world. Shipping costs will apply, and will be added at checkout. We run discounts and promotions all year, so stay tuned for exclusive deals.

How much does shipping cost and when will I see the total?

Depending on where you're located, small parts can ship free. Large parts like bumpers, hoods, and body kits require freight shipping. Uou'll see the exact cost at checkout before you pay. Freight usually runs $150-$300 depending on size and your location. We know it's expensive. We negotiate the best rates we can. If you're ordering multiple large parts, text us. We can sometimes combine shipping and save you money. We're not hiding fees in the final step. What you see at checkout is what you pay.

How long will it take to receive my order?

It depends on where you are. Orders processed here will take 5-7 business days to arrive. Overseas deliveries can take anywhere from 7-16 days. Delivery details will be provided in your confirmation email.

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