The fuel filler neck is a relatively simple component. The visible part is the inlet for the fuel nozzle where you fill the gas tank.
After that, there’s a pipe extension that goes down to a rubber hose, which, in turn, goes to the fuel tank. There’s also a second smaller pipe that catches the overflow, which is also connected to the fuel tank.
On some filler neck assemblies, there’s an air filter built-in as well, which is a part of the evaporative control system. This allows clean air into the tank to offset fuel as it is used by the engine. Most fuel filler necks also have a ground strap, which prevents static discharges that could ignite the fuel vapour.
Cost of Fuel Filler Neck Replacement
On average, it should cost about £175 to replace the fuel filler neck on most vehicles.
Using £100 per hour as the labour rate for factory repairs and £70 per hour for non-factory repair shops, a few examples of the fuel filler neck replacement cost on some common vehicles are presented below:
- For a 2003 Toyota Camry with a 2.4-liter engine, the labour time to replace the fuel filler neck is estimated at 0.7 of an hour. A factory replacement part costs about £190, and a non-OEM part costs about £90. The total cost to complete the job would be about £240 using factory parts and about £140 using aftermarket parts.
- For a 2008 Nissan Altima with a 2.5-liter engine, the labour time to replace the fuel filler neck is estimated at 3.7 hours. In this case, it’s necessary to remove the fuel tank to access the connections. A factory part costs about £140, and a non-OEM part costs about £60. The total cost for this job would be about £400 using factory parts, and about £320 using aftermarket parts.
- For a Subaru Legacy with a 2.5-liter engine, the labour time to replace the fuel filler neck is estimated at 0.7 of an hour. A factory replacement part costs about £110, and an aftermarket part costs about £55. This makes the job about £160 to complete using OE parts, or about £105 using aftermarket parts.
- For a 2009 Ford F150 with a 5.4-liter engine, the labour time to replace the fuel filler neck is estimated at 1.3 hours. A factory replacement part costs about £600, and a non-OEM component costs around £230. This makes the job about £690 in total, using factory parts, and about £320 using aftermarket parts.
Fuel Filler Neck Replacement
The main issue with fuel filler necks is rust. They are usually made of galvanised or painted steel. However, their critical parts are underneath, where they’re vulnerable to road salt, road spray, condensation, etc.
The next thing that usually goes wrong with filler necks is physical damage, such as being too rough while filling the tank, or perhaps forgetting the nozzle is installed and driving away.
If a fuel filler neck develops corrosion that leads to a leak there, it will cause an evaporative system leak fault. Another sign is the smell of fuel if vapours can escape.
The evaporative control system must hold the vacuum in the fuel system during the purge cycle when fuel vapours are recycled into the intake. This includes the gas tank, the evaporation canister, and the fuel fill hoses and fill neck.
Replacement involves unbolting the filler neck from the bodywork, and then undoing the hose attachments and the ground strap. Access is usually restricted under the vehicle, but once you reach there, the attachments are quite simple.
How to Tell if a Fuel Filler Neck Needs to be Replaced
The obvious sign would be if there is a smell of fuel at the filler due to leaks. The system needs to be sealed there, and a pinhole leak or crack can show wetness or seepage. Most often, that’s not noticeable.
The first sign of a problem is more often a code set for an evaporative system leak. In that case, one part that’s hard to rule out and very easy to replace is the gas cap, which needs to seal against the top of the filler neck. A leak there will set the leak code, and a £5 fuel cap fixes it sometimes.
If the easy way doesn’t take care of it, then the usual next step is a smoke test. This pumps a smoky vapour into the gas tank through the filler neck or an evaporation port and checks for leaks.
There are a lot of places that can leak, but if the leak is at the filler neck, then the solution is to replace that part. Most often, there is an hour of diagnostic labour involved to figure out where the leak is.
On a newer style filler neck that uses a locking flap seal and no gas cap, sometimes the spring mechanism that brings the internal port cover up and holds it sealed can fail. That’s usually quite obvious. It must come up solidly and hold its position, and if it doesn’t, the filler neck won’t seal and needs to be replaced.
Generally, yes, it would set a trouble code to check the evaporative system for leaks.
It depends on how bad it is. A very small leak would only show up as a vacuum leak in the EVAP system, while larger leaks can cause fuel and fuel vapour leaks, which can be dangerous.
Most of the time it takes a little over an hour to replace.