Installing a charcoal canister is straightforward — most builders have it done in under an hour. The mistakes that cause problems all come down to the same few details: mounting height, hose routing, fitting selection, and what happens at the atmosphere side. Here's how to do it right the first time.
What you need
- Vapor Trapper™ canister in the right size for your build (see our sizing guide)
- Fittings appropriate to your tank vent — barb, -6 ORB, or 1/8" NPT (the Combo Kit includes the common ones)
- Mounting clamps — Dell-style or billet billet aluminum
- Fuel-rated 3/8" or 1/4" rubber hose, cut to length (cut-to-length hose)
- Mounting screws (screw kit)
- Optional: K&N slip-on filter for dust-prone or marine environments
Step 1: Find the tank vent
Locate the vent fitting on your fuel tank. On factory tanks, it's typically a small barb or threaded fitting separate from the fuel pickup and the filler neck. On aftermarket fuel cells, it's usually a -6 ORB or AN port labeled "vent." On older vehicles with no dedicated vent, you may be venting through the gas cap — replace the cap with a sealed one and add a vent fitting to the tank or filler neck.
Step 2: Pick a mounting location
The canister must mount above the tank's high-fuel level. This is the single most important rule. If the canister sits at or below tank level, liquid fuel will run up the vent line into the charcoal media — saturating it instantly and creating a fire hazard.
Common mounting locations:
- Frame rail above the tank — works on most hot rods and trucks
- Inner fender or firewall — clean and visible
- Bulkhead in engine compartment — common for marine
- Direct to fuel cell — for race-style installs with -6 ORB ports on the cell
Step 3: Mount the canister
Mark your mounting holes, drill, and bolt the canister in place using the included clamps. The canister should be oriented with the fittings pointing in a sensible direction for hose routing — usually one fitting toward the tank, the other toward open atmosphere or a filter.
Tighten the clamps so the canister doesn't rotate, but don't crush it. Hand-tight plus a quarter-turn with a wrench is usually right.
Step 4: Plumb the tank-side hose
Cut a length of fuel-rated hose long enough to run from the tank vent fitting uphill to the canister inlet, with no dips or low spots. Any low spot creates a place for liquid fuel or condensate to pool.
Push the hose onto the barb fittings firmly — they should require effort to seat. Secure each end with a hose clamp (if you're using barb fittings; -6 ORB connections seal with the O-ring).
Step 5: Plumb the atmosphere side
The other end of the canister vents to atmosphere. You have three options:
- Open barb — simplest, but leaves the charcoal exposed to dust and water from below
- Short hose pointed downward — keeps water and dust out, no extra parts
- K&N slip-on filter — best protection for off-road, dusty, or marine environments. Filters incoming air so the charcoal stays clean
Step 6: Verify the install
- Confirm the canister is above the tank's high-fuel level
- Confirm the hose runs uphill from tank to canister with no low points
- Confirm hose clamps are tight and there are no leaks
- Fill the tank, let the vehicle sit for 24 hours, then sniff around the canister and connections — if you smell fuel, you have a leak somewhere
Common mistakes
- Mounting too low. The single most common error. Liquid fuel runs into the canister, ruins the media, creates fire risk.
- Using non-fuel-rated hose. Vinyl or non-rated rubber will swell, harden, or leak vapor through the wall.
- Skipping the atmosphere-side filter on dusty rigs. Off-road dust packs into the charcoal and reduces flow.
- Plumbing both fittings to the tank. The canister has an inlet and a vent — only one connects to the tank.
If you've got a question on a specific install — tank type, vehicle, mounting situation — reach out. We've seen most configurations.
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