flyboy
16-08-2012, 09:07 AM
Had my wife report this recently from her third gen, and confirmed that there was a terribly strong fuel smell after driving the car, eminating from the fuel filler area.
Searching through threads here found that those with the same problem fixed this with a new fuel cap (those with sulphur egg smell obviously had a different problem and fixed with a new oxygen sensor or replacing the cat converter).
The general consensus seemed that the internal valve in the fuel cap was getting stuck/worn and was causing the smell.
The new, genuine part was only going to be $20.10, so I decided to pull the old cap apart and see what was going on.
After a bit of prying and poking, I managed to disassemble the cap. Interestingly, the internal valve (which allows pressure equalisation if the fuel heats up, and allows the tank to fill with air as fuel is used) was in mint condition. The rubber was new/soft and the springs were intact.
I reassembled the valve, and then removed the main rubber seal (which sits on the outside of the filler cap), cleaned it up and replaced. I did notice the ratcheting of the cap is very "light" and appears to happen with little force. I noticed the plastic notches (both on the black plastic outer, and white plastic inner) which control the ratcheting were both worn.
So what I think is happening - as the fuel cap gets older (and perhaps in winter when it shrinks slightly), the worn plastic notches mean that the ratcheting occurs EARLIER than usual and the cap isn't being screwed in as tight to the tank receptacle. This means the main rubber seal is sitting slightly off the tank, and vapours are escaping.
Our fuel smell has gone away by simply squeezing the fuel cap with brute force while screwing it in - this extra friction between the white and black plastic on the cap delays the ratcheting, and allows the cap to screw in further... this pulls the rubber seal onto the metal face of the tank receptacle - bingo, no more fuel smell.
What is the point of this post? I don't really know! In the long term, still going to need a new fuel cap. But the internal valve is not the problem (well wasn't in our case). The problem is the ratcheting system becomes worn and the cap is not screwing in far enough.
I will however, be telling my wife once we get a new cap, not to turn it more than one damn click! Turning it more than this is obviously going to accelerate the wear.
Searching through threads here found that those with the same problem fixed this with a new fuel cap (those with sulphur egg smell obviously had a different problem and fixed with a new oxygen sensor or replacing the cat converter).
The general consensus seemed that the internal valve in the fuel cap was getting stuck/worn and was causing the smell.
The new, genuine part was only going to be $20.10, so I decided to pull the old cap apart and see what was going on.
After a bit of prying and poking, I managed to disassemble the cap. Interestingly, the internal valve (which allows pressure equalisation if the fuel heats up, and allows the tank to fill with air as fuel is used) was in mint condition. The rubber was new/soft and the springs were intact.
I reassembled the valve, and then removed the main rubber seal (which sits on the outside of the filler cap), cleaned it up and replaced. I did notice the ratcheting of the cap is very "light" and appears to happen with little force. I noticed the plastic notches (both on the black plastic outer, and white plastic inner) which control the ratcheting were both worn.
So what I think is happening - as the fuel cap gets older (and perhaps in winter when it shrinks slightly), the worn plastic notches mean that the ratcheting occurs EARLIER than usual and the cap isn't being screwed in as tight to the tank receptacle. This means the main rubber seal is sitting slightly off the tank, and vapours are escaping.
Our fuel smell has gone away by simply squeezing the fuel cap with brute force while screwing it in - this extra friction between the white and black plastic on the cap delays the ratcheting, and allows the cap to screw in further... this pulls the rubber seal onto the metal face of the tank receptacle - bingo, no more fuel smell.
What is the point of this post? I don't really know! In the long term, still going to need a new fuel cap. But the internal valve is not the problem (well wasn't in our case). The problem is the ratcheting system becomes worn and the cap is not screwing in far enough.
I will however, be telling my wife once we get a new cap, not to turn it more than one damn click! Turning it more than this is obviously going to accelerate the wear.