The brief
Mr Jason's Q5 had a petrol smell lingering in the cabin, and it was getting stronger. He brought it in. A petrol smell that's getting worse is not something to leave, a fuel leak near anything hot is a real hazard, and a stronger smell means the leak is growing. The in-tank fuel pump module sits on top of the fuel tank, sealed in with a large rubber ring, and it pumps fuel up to the engine. Over the years that sealing ring hardens and shrinks, so it stops sealing cleanly and fuel vapour, and sometimes a trace of liquid fuel, escapes around it, and on a Q5 that's right under the cabin floor, so the smell comes through into the car. The pump itself can be on its way out too. A hardened seal doesn't reseal, so the pump module and its sealing ring need replacing.
The diagnosis
A check, with the fuel system inspected and the tank top accessed, traced the smell to the in-tank fuel pump module, fuel vapour escaping around its hardened sealing ring. The pump was also showing signs of age. The fuel lines, the filter and the rest of the system checked out. That's a fuel pump module and seal replacement, a complete module with a fresh sealing ring, fitted properly so it seals.
The work
The fuel system pressure was relieved, the access to the tank top opened up, and the old in-tank fuel pump module removed along with the hardened sealing ring. A new genuine Audi-spec fuel pump module was fitted with a fresh sealing ring, seated properly, the system primed, and checked carefully for any leak or smell. A road test, with the car warmed up, confirmed no petrol smell, a clean start, and steady running.
The outcome
No more petrol smell in the cabin, the fuel pump module sealed and dry, and no fuel-leak risk. The Q5 went home with the leak sorted at its source. A hardened fuel pump seal only leaks worse and the vapour comes straight into the cabin, so renewing the module and the seal stopped it for good, the kind of job worth doing properly and quickly.
