fuel smell

UK forum for general and technical discussion about the Z3 roadster
Post Reply
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

fuel smell

Post by resunoiz »

as everytime, I filled engine to full tank. gone home, nothing but engine indicator a 3/4, not moving. I did'nt care too much about, is not the first time it goes "sleep" and starts whenmever he wants.
had lunh, and at 16.00 pm took the car, made 5-6 turn on the city, and the indicator always a 3/4, not moving.
suddenly in the sterets, an intense, very intense fuel smell. had to stop, very afraid honestly, shut down the car. checked the fuel cap was ok (think it was), no leaks. the smell seemed from inside, NOT so strong outside.
restarted the car, little anxious, the engine indicator slowly went to full (as it should). the smell slowly went away, is slightly perceptible now, I think because it was veeery strong and quite hard to leave. interior carpet is dry, the 3 hoses from the tank under the car seems ok.

what to check? I'm a bit afraid....
Clivebse
Joined: Sun 15 Sep, 2013 22:09
Posts: 63

  M roadster S50
Location: Suffolk

Re: fuel smell

Post by Clivebse »

The fuel tank level sensors are behind the seat backs. You have to cut the carpet to get to them, that's how you can tell if anyone has ever been there before.
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

yes, know it. but "how" and "what" to check?
someone has had any similar trouble? I readed a lot of different causes about it..
User avatar
Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: fuel smell

Post by Southernboy »

OK...First thing...whenever I fill up, I always tell the attendant to fill it - "Auto stop"...this means he starts the pump, and when it automatically clicks off, I don't "sqeeze" in another litre or whatever...this prevents any spillage when cornering with an overfull tank.
Second..if the cap isn't on properly, it will leak fuel which will evaporate and fumes will enter the car...The fuelcap is literally right by the window!!!

The issue with the 3/4 indication isn't serious...it is a faulty fuel level sensor.. This sensor is part of the fuel pump located inside the fuel tank. It is actuated by a 3mm D arm with a small plastic float at the end...the float raises and lowers according to the quantity of fuel in the tank...at the other end of the arm it attaches to the fuel pump assembly and has a brass contact which arcs over a coil...this coil prvides a resistance much like a dimmer switch, and transmits the electrical signal to the fuel guage on your dash.
To remove the fuel pump, you need to remove the right hand seat, and open the access through the carpet behind the seat. You will now need to remove the coverplate which has a rubber gasket. It is held by 3 screws spaced 120 degrees on the circumference of the plate. You will see 2 hoses connected to the doorway, which is retained by a large (120mm+ D) plastic screw on flange. Once you remove this flange and detach the hoses and the electrical, you can lift out the fuel pump assembly...it is important to note that you cannot do this job without having the fuel in the tank at practically empty...if not, the fuel in the tank will pour into the car from the doorway to the fuel pump when you unscrew the flange fastener...you will need 2 small hose clams (15 - 18mm) to replace the crimp type clamps when you reassemble.
Servicing the fuel sender id very simple...thoroughly clean the contact faces of the arm, and the "coil" it mates with...If you can, slightly bend the arm so it makes better contact onto the coil. It loses it's proximity to the coil purely from wear over the years.
Image
"Normal is overrated"
Image

Z3 Upgrades and Additions
User avatar
Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: fuel smell

Post by Southernboy »

In the pic I posted, you can see the black plastic float, and the arc of the coil where it transmits the level signal.
It is important to replace the hoses onto their respective nozzles...one is "in" and the other "out" for the flow of fuel...Also, very important to replace the fuel pump assembly at the exact same position it was before you removed it..best to use a permanent marker or suchlike to mark it's relative position before you undo the flange fastener... :wink:
"Normal is overrated"
Image

Z3 Upgrades and Additions
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

OK...First thing...whenever I fill up, I always tell the attendant to fill it - "Auto stop"...this means he starts the pump, and when it automatically clicks off, I don't "sqeeze" in another litre or whatever...this prevents any spillage when cornering with an overfull tank.
I always do the same.
Second..if the cap isn't on properly, it will leak fuel which will evaporate and fumes will enter the car...The fuelcap is literally right by the window!!!
yes, I tought. BUT I was with cloed windows and the smell was stronger inside than outside...
The issue with the 3/4 indication isn't serious...it is a faulty fuel level sensor.. This sensor is part of the fuel pump located inside the fuel tank. It is actuated by a 3mm D arm with a small plastic float at the end...the float raises and lowers according to the quantity of fuel in the tank...at the other end of the arm it attaches to the fuel pump assembly and has a brass contact which arcs over a coil...this coil prvides a resistance much like a dimmer switch, and transmits the electrical signal to the fuel guage on your dash.
infact, I never cared about it. but this operating way "new", most cases it goes to zero and then to full immediately, never stopped in the middle. I tought thre may be a correlation, don't know.
To remove the fuel pump, you need to remove the right hand seat, and open the access through the carpet behind the seat. You will now need to remove the coverplate which has a rubber gasket. It is held by 3 screws spaced 120 degrees on the circumference of the plate. You will see 2 hoses connected to the doorway, which is retained by a large (120mm+ D) plastic screw on flange. Once you remove this flange and detach the hoses and the electrical, you can lift out the fuel pump assembly...it is important to note that you cannot do this job without having the fuel in the tank at practically empty...if not, the fuel in the tank will pour into the car from the doorway to the fuel pump when you unscrew the flange fastener...you will need 2 small hose clams (15 - 18mm) to replace the crimp type clamps when you reassemble.
Servicing the fuel sender id very simple...thoroughly clean the contact faces of the arm, and the "coil" it mates with...If you can, slightly bend the arm so it makes better contact onto the coil. It loses it's proximity to the coil purely from wear over the years.
my goal is to not remove the pump, but verify the gasket and the cover cap is correctly tighten.

the cover cap closes clockwise or anti-clockwise?
User avatar
Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: fuel smell

Post by Southernboy »

Cover cap closes clockwise....The erratic indicator is a result of the float / coil contact which is part of the fuel pump....mine did the same...indicated empty then popped up to full...then started to indicate half or quarter etc tc...It will eventually fail completely and require servicing. The smell of fuel in the car is definitely not caused by a leak inside the car..as the only place this can happed is via the entry to the fuel pump as I described above...if this was leaking, it would be unbearable inside your car constantly because of fuel fumes. It would soak into the carpet behind the seat and would be extreme intense fuel atmosphere in the car all the time.
"Normal is overrated"
Image

Z3 Upgrades and Additions
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

maybe is simpy slightly untighted, via roads irregularities and vibrations. and is the easiest and cheaper thing to verify...

the smell lasted less than 30 second but was really intense. came from inside the car, under passenger seat. quite sure.
User avatar
Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: fuel smell

Post by Southernboy »

Trust me...to loosen that cover is extremely difficult...If it was loose and leaking, you would have a constant smeel of petrol in the car...I suspect you didn't replace the fuel cap after filling... :wink:
"Normal is overrated"
Image

Z3 Upgrades and Additions
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

Southernboy wrote:Trust me...to loosen that cover is extremely difficult...If it was loose and leaking, you would have a constant smeel of petrol in the car...I suspect you didn't replace the fuel cap after filling... :wink:

is the first thing I'll obviously check ;)

but the loosen cover was a fault discovered by a discreet number of italian folks.
User avatar
Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: fuel smell

Post by Southernboy »

The cover behind the carpet is removed by 3 screws (self tapping)...behind that you will see the 2 hoses attached to the 2 nozzles...it may be that one of them may have a small leak...but for the screw on fuel pump lock cover to come undone is not possible...it has a rubber washer between it and the fuel tank, and you will require a special tool or some ingenuity to to undo this large cover...also it must be torqued when re-fitting, and if you know about plastics, once it is correctly torqued, it compresses the rubber washer, and will not undo. The size of it is aprox 120mm diameter or there-about...I had to use a piece of oak and a hammer to slowly slowly tap it on it's serated edge to get it to undo...re-fitting it required lubricating the threads so that it would make replacing a little easier..it is a very coarse thread, and can be cross threaded quite easily if unlubricated, and working in such a confined space with a carpet which is trying to get in the way as much as it can...not a comfortable task...anyhow, I can say with certainty, that it will not be the source of your concerns...only the hoses may be leaking, but if that were true, you would have a constant smell of fuel in the car. As you said, it dissipated after 30 minutes, and that leads me to say you messed up replacing the cap after filling, and some fuel was spilt into the "cup" area of the filler point.
"Normal is overrated"
Image

Z3 Upgrades and Additions
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

Southernboy wrote:The cover behind the carpet is removed by 3 screws (self tapping)...behind that you will see the 2 hoses attached to the 2 nozzles...it may be that one of them may have a small leak...but for the screw on fuel pump lock cover to come undone is not possible...it has a rubber washer between it and the fuel tank, and you will require a special tool or some ingenuity to to undo this large cover...also it must be torqued when re-fitting, and if you know about plastics, once it is correctly torqued, it compresses the rubber washer, and will not undo. The size of it is aprox 120mm diameter or there-about...I had to use a piece of oak and a hammer to slowly slowly tap it on it's serated edge to get it to undo...re-fitting it required lubricating the threads so that it would make replacing a little easier..it is a very coarse thread, and can be cross threaded quite easily if unlubricated, and working in such a confined space with a carpet which is trying to get in the way as much as it can...not a comfortable task...anyhow, I can say with certainty, that it will not be the source of your concerns...only the hoses may be leaking, but if that were true, you would have a constant smell of fuel in the car. As you said, it dissipated after 30 minutes, and that leads me to say you messed up replacing the cap after filling, and some fuel was spilt into the "cup" area of the filler point.

you don't know how I hope it ;)

I'll post updates at post refills.
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

Image

I noticed the cap seal is wet in the center, BUT in the external aprt too..may be a sign of a failure of it, removing in fact a lot of my troubles?

in your cars, when you remove the cap, is wet to the external part fo that seal too, or not?
User avatar
Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: fuel smell

Post by Southernboy »

I have never noticed that ...I'll check and let you know...I think maybe your tank has been filled too much...?
"Normal is overrated"
Image

Z3 Upgrades and Additions
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

Southernboy wrote:I have never noticed that ...I'll check and let you know...I think maybe your tank has been filled too much...?
ithis pic is made with 3/4 fuel tank. I didn't refilled till the smell of last saturday (and not noticed any new smell, hpefully)

mah...I don't know...in effect last refill was in a "new" for me fuel station, but I stopped at first click, as you explained and I always do.
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: fuel smell

Post by Del »

Yep - mine is often a bit wet with what I assume is condensed petrol vapour. When I bought the car I noticed that rubber seal was badly perished and cracked and after searching UK BMW dealers nationwide, I found a few still in stock and managed to get a new one. However, I have never suffered from a petrol smell either in or around the car.

The only time I have had a petrol smell problem (on a different car) was when a poor quality rubber fuel pipe was leaking. BMW rubber fuel pipe is very good quality and so I wouldn't guess at that being the problem. What about the o rings on the injectors? Is the smell in the engine bay? Fumes from the engine bay might well blow inside the car via the heater vents. Have you had any work done in the area of the injectors?

Finally, I believe there is some system where fumes from the fuel tank vent off into a charcoal canister in the engine bay (I'm not 100% familiar with the system) could this be the problem i.e. loose pipe or slight blockage?
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

Del wrote:Yep - mine is often a bit wet with what I assume is condensed petrol vapour. When I bought the car I noticed that rubber seal was badly perished and cracked and after searching UK BMW dealers nationwide, I found a few still in stock and managed to get a new one. However, I have never suffered from a petrol smell either in or around the car.

The only time I have had a petrol smell problem (on a different car) was when a poor quality rubber fuel pipe was leaking. BMW rubber fuel pipe is very good quality and so I wouldn't guess at that being the problem. What about the o rings on the injectors? Is the smell in the engine bay? Fumes from the engine bay might well blow inside the car via the heater vents. Have you had any work done in the area of the injectors?

Finally, I believe there is some system where fumes from the fuel tank vent off into a charcoal canister in the engine bay (I'm not 100% familiar with the system) could this be the problem i.e. loose pipe or slight blockage?
is from the rear, so near the fuel tank...not from the engine. thanks for yor "report" ;)
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

this afternoon made some check.
fuel pump "cap" is tighten, no signs of something that could have "wetted" the surfaces.
no smell at all, even moving the hoses.
Image

seeing the fuel cap terminal, saw some points to pay attention at:
- rubber gasket that is around the metal part of the tank was heavily rotten in various points, fuel that eventually can came there could go anywhere;
- the hose that connects this rubber gasket to the bottom of the car was detached (I knew it)
- the terminal part of the plastic tank where the filler cap screws on, is in metal (pic below). had 2-3 rectangular little cramps around it. one of them in the moment I touched it, fall under the chassis. what are they for? maybe to tighten the plastic and the metal parts together?
- is normal that this tank part lean on the car chassis? (pic below)

Image

sorry for my bad english, think is hard to understand :P
User avatar
Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: fuel smell

Post by Southernboy »

Looks as though your fuel tank straps have shifted...the tank filler tube should not rest on the car. I suggest you raise the car, loosen, but do not remove the strap bolts (2) and then have someone on the outside lift the tank filler tube to a central position so it doesn't touch the body, and while they hold it in position, you re-tighted the straps...repeat until you have the tank filler tube in the correct position central to the rubber surrounding gasket... :wink:
PS...Might be an easier job to do if the tank is almost empty before you start...Also, make sure the rubber "cushioning strips between the straps and the tank are in position...there are rubber pieces at top corners and bottom corners of the tank where the starps fold around the tank :wink:
"Normal is overrated"
Image

Z3 Upgrades and Additions
User avatar
Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: fuel smell

Post by Southernboy »

Finally...clean your car properly...that area behind the carpet look like it's been overly neglected...bad boy!!! :roflmao:
"Normal is overrated"
Image

Z3 Upgrades and Additions
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

tzè shut up southworld boy :D

can you verify me if under the rubber gasket the fuel tank lines on the cas chassis please? :D
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

update.

made a lot of km till the episode mentioned, no any other gas smell. even with the old gasket, that saturday I replaced in any case, just to be sure.

I almost certanly leaved the cap half open :P

I now have to know why my fuel thank "leans" on the car chassis, as pic post above. maybe tell me about yours! :D
User avatar
lordhelpus
Joined: Sat 14 Sep, 2013 09:46
Posts: 128

  Z3 roadster 2.8
Location: Tax Exile

Re: fuel smell

Post by lordhelpus »

Like southernboy has said before in a previous post your fuel straps holding your tank have broken or shifted get to them and check, when that tank is full that's a lot of weight in that tank? Try moving the fuel filler spout (the bit where you put the fuel nozzle in) about if its very loose your tank straps have broken.
1997 2.8................ Montreal Blue
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

lordhelpus wrote:Like southernboy has said before in a previous post your fuel straps holding your tank have broken or shifted get to them and check, when that tank is full that's a lot of weight in that tank? Try moving the fuel filler spout (the bit where you put the fuel nozzle in) about if its very loose your tank straps have broken.
i checked a lot of time them, they're tightened :)
User avatar
Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: fuel smell

Post by Southernboy »

You need to slacken the straps, then re-position the tank so that it does not rest against the car, and then re-tighten the straps again... :wink:
"Normal is overrated"
Image

Z3 Upgrades and Additions
resunoiz
Joined: Tue 04 Sep, 2012 16:12
Posts: 162

  Z3 roadster 1.9

Re: fuel smell

Post by resunoiz »

made this at least 2 times...probably they are in some way "pampered". I have to try adding some tickness..
Post Reply