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.
1994 Audi 90 CS QuattroFACTORY OEM SERVICE PROCEDURE
Transfer Pump Fuel Volume Check
- Turn ignition off. To check transfer pump (in tank), remove rear seat. Remove fuel sending unit access cover. Disconnect ignition coil secondary wire and jumper to ground.
- With transmission in Neutral, crank engine for 3-4 seconds. While starter is turning and for a few seconds afterwards, an audible sound should be heard at the pump. If sound is not heard, go to next step. If sound is heard, go to step 5).
- Remove fuel pump relay from relay panel. Activate fuel pump using Remote Control (VAG 1348/3A). If pump does not operate, disconnect fuel pump wire harness connector. See Fig 1 .
- Using test light, check voltage between Brown wire and Red/Yellow wire. If voltage is present, replace fuel pump. If voltage is not present, repair open or short circuit in wiring.
- Remove fuel pump relay. Disconnect and plug transfer pump output hose. Attach a hose to pump outlet connector and place other end of hose in a graduated container. Activate fuel pump for 10 seconds.
- Minimum fuel flow should be 10 ounces (.3 liter). If fuel flow is low, check fuel tank filter for restriction. If fuel tank filter is okay, replace fuel pump.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.
