Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fuel Tank Vapor Control Valve Test
2004 Acura 3.5RLSECTION Fuel Tank Vapor Control Valve Test
- Ensure fuel tank is less than half full. Remove fuel filler cap. Disconnect fuel tank vapor signal hose. See Fig 1 . Disconnect vacuum hose from EVAP canister, then plug ports with plugs. Connect vacuum pump/gauge to EVAP canister vent shut valve port. See Fig 2 . Apply vacuum with vacuum pump/gauge (80 pumps). If vacuum holds, go to next step. If vacuum does not hold, go to step 3 .
- Connect a second vacuum pump to fuel tank vapor signal tube. See Fig 1 . Apply vacuum with vacuum pump (1 pump). Check vacuum reading at vacuum pump/gauge used in step 1) . If vacuum holds, replace fuel tank vapor control valve. See EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL & INSTALLATION article. If vacuum is released, fuel tank vapor control valve is okay. Go to step 4 .
- Disconnect fuel tank vapor quick-connect fitting from EVAP canister. Cap port on canister. Reapply 80 pumps of vacuum with vacuum pump. If vacuum holds, replace fuel tank vapor control valve. See EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL & INSTALLATION article. If vacuum does not hold, check EVAP canister vent shut valve "O" ring. If "O" ring is okay, replace EVAP canister and go back to step 1 .
- Fill fuel tank with fuel. Check for fuel in hoses at 2-way valve and fuel tank vapor recirculation hose. See Fig 3
. If fuel runs out of hoses at either location, replace fuel tank vapor control valve. See EMISSION SYSTEMS & SUB-SYSTEMS
in REMOVAL & INSTALLATION article. If fuel does not run out at either location, the fuel tank vapor system is operating normally.NOTE: Tiny droplets of fuel at either location is normal.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.