This is a modification, not a repair. It removes the car's evaporative emissions control. The author says plainly that the car is no longer Euro 4 compliant. Check what it means for road use, MOT and insurance where you live before doing it. It also changes where fuel vapour goes. The owners who have done it report no smell or problems, but one forum member recalled a fire attributed to this kind of change, which nobody could confirm (see below). Fuel vapour is flammable, so make sure everything you leave is securely clamped and leak-free.
This guide eliminates and simplifies the fuel vapour (evaporative emissions) system that sits above the offside rear wheel. It looks like a worrying job but is really easy, and the finished job is very simple to check by eye. You need to take the rear clam off to get to it, which can take several hours. See Rear clam removal. The actual work took the author about 30 minutes.
Help wanted
The thread's labelled photos (which the lettered parts refer to) are no longer available, so there are no pictures here, and I've described each part by name, with the author's letter in brackets so you can match it against the thread. The thread's step list also repeats one step (see below). If you have photos of the system before and after, they would make this guide much clearer.What you are looking at
The parts, as the author labelled them in his photo:
- A: 18 mm internal diameter hose from the fuel filler neck to the vapour exchange box (E).
- B: 8 mm hose from the roll-over valve (C) to the carbon canister (D).
- C: the roll-over valve. It lets vapour through when the car is upright and blocks it when inverted.
- D: the carbon canister.
- E: the vapour exchange box (the author's name for it, "for want of a better term").
- F: a 3-way joiner with three 8 mm hoses off it.
- G: an 18 mm hose that comes up from the tank.
- H and J: two 8 mm hoses that come up from the tank.
- K: 8 mm hose from the carbon canister to the purge solenoid.
- L: hard pipe from the solenoid to the inlet manifold (not shown in the author's photos).
Removing it
- Remove the carbon canister (D) and scrap it.
- Remove the vapour exchange box (E).
- Remove hose A.
- Remove hose K, and the hard pipe L. The thread's list says "remove and scrap L" twice. The second one may mean the solenoid, but the author doesn't say.
- Remove the 3-way joiner (F) and its three short hoses.
- Keep hose B. Feed it down from the roll-over valve (C) into your wheel arch area, so it vents fuel vapour there. You can extend it if you need to.
- Connect hose G to the fuel filler neck.
- Connect hose H to the bottom of the roll-over valve (C).
- Double check all the Jubilee clips and joints are done up firmly.
- Optionally fit a gauze filter on the end of hose B, though the author doubts it is vital.
What you are left with
Three pipes come up from the tank:
- Hose G, connected to the fuel filler neck.
- Hose J, which must be terminated or blocked. The author used an 8 mm bolt with a non-threaded shank.
- Hose H, which leads from the tank to the bottom of the roll-over valve (C).
This lets the tank vent excess pressure and keeps the roll-over valve in case the car is inverted. Two other posters thought hoses J and the joiner (F) are just vents from different parts of the tank, and that you could join J into H with a Y piece instead of blocking it (one has done this). The author says it works but there is no functional benefit, which is why he just blanked it. The weight saving is about 1.2 kg.
Discussion from the thread
- Could the vent go to the engine inlet instead? One member asked whether the roll-over valve output should go to the inlet before the throttle body, so the vapour is burnt and the tank is protected by the air filter. The author agreed it would be theoretically safer for fumes. But on a boosted car you must be sure there is a working one-way valve between the inlet and the roll-over valve, or you will pressurise the fuel tank, which could burst it. Even with the valve, idle vacuum could strain the tank, and the pressure changes could cause odd idling. He vents to atmosphere for this reason. He also points out that hundreds of millions of cars did this before Euro 4.
- Fire risk. One member remembered a car catching fire from fuel vapour around the engine after this was removed. Both he and the author searched and found nothing confirming it. The author's view is that if it happened, something must have been done wrongly, because venting into the wheel arch has no naked flame and any fumes blow away in the wind. Treat this as unconfirmed, but secure fittings matter.
- Smell. The author reported no fuel smell after a few miles, or after the car sat in a hot garage. Another owner who has removed the system has had a hot garage and no smell either, and one owner did track days and road driving for about a year with the same setup.
- Keeping the solenoid? One owner's solenoid ticked loudly after a supercharger was fitted. Strapping the solenoid to the engine mount bracket (engine side) with cable ties stops it being heard in the cabin. The solenoid is dead weight anyway on an aftermarket ECU. Check what your ECU expects before deleting the solenoid.