Cabin fuel smell & E31 fuel ventilation system

[alex840]

Jaydog101,So utilizing the middle nipple and capping off the bottom has worked out for you?

[Fatandre]

So what is the proper way to block this as I have seen 2 examples who have blocked the opposite one.

[Willett1]

Hi, I have the same problem with the ventil valve i believe, but bmw tell me they no longer manufacture the part. Anyvody know where i can get one... Thanks

[amurphCA]

Hi, I have the same problem with the ventil valve i believe, but bmw tell me they no longer manufacture the part. Anyvody know where i can get one... Thanks

Also looking, I'm also doing reserch on what to use instead. It looks like audi may make something that will work, but will require modification.
https://www.ecstuning.com/b-genuine-...ve/4b0201766b/

If you find a more legitimate part please let me know.

[JDP530]

Here is the Audi valve on ebay for $30: https://www.ebay.com/itm/NEW-GENUINE...-/183619367673

[Fatandre]

Here is the Audi valve on ebay for $30: https://www.ebay.com/itm/NEW-GENUINE...-/183619367673

Will the audi one work?

[DavesNotHere]

The Audi valve will "technically" work, as would any similar liquid-blocking fuel return valve. Mounting it and adapting hose fittings would be the worst part of the job.
It seems to me that cutting the mounting tabs off the old valve (keeping part of the valve cylinder section intact) and using a hose clamp or two to hold the Audi filter to the tabbed section, would work, or even a piece of metal plumber's tape and some flat rubber (like a split hose); ugly, but functional.

The float valve in it prevents liquid fuel from getting into the carbon canister, or worse flooding the engine to the point that a hydraulic lock could occur if enough fuel gets into the canister that it pushes into the intake and enough liquid fuel enters a cylinder. That kind of thing could happen without fuel expansion from temperature if the car is parked on an incline* such that the fuel level in the tank is higher than highest loop of line leading to the carbon canister (and intake, in the worst case). A simple Tee would solve the gas tank pressure issue, but would not prevent liquid fuel from possibly getting to where it shouldn't go, which could even happen with spirited driving. <-- My 2-cents. I have not yet addressed my fuel tank pressure issue, but will get around to it shortly.

*If you've seen pictures of cars parked in San Francisco, you'll get the idea...

[cartoonz]

forget the Audi valve....
Nissan Skyline R52...
https://www.ebay.com/p/1417865755

another member here did this, read 1/2 way down the page:
http://km5tz.com/BMW%20850iP5.htm

[TedBobo]

Thanks!

[JDP530]

I am using the Nissan fuel vent on my '91 model. It has helped with re-fueling but I still cannot fill tank at full flow without handle shutting off so I have to fill tank slowly. I made up a bracket out of some .063" alum. I bought the vent from tasca parts but it took a couple of weeks to get it.
https://www.tascaparts.com/oem-parts...lve-1737089900

[raineycd]

I just took the valve out and bypassed it with a 90* connector. No valve, no problem!

[Fatandre]

I just took the valve out and bypassed it with a 90* connector. No valve, no problem!

Is that a good idea?

[raineycd]

Is that a good idea?

Keep the shiny side up and it's fine.

[Willett1]

Just want to recap, i have had my 850i for a while now and it drives perfectly (usually) but i can only half fill the fuel tank otherwise i get a big puddle appear under the car. There is no tank pressure when i take the fuel cap off. I have jacked the car up and removed the vent valve blowing it through and it seems to work although i dont know exactly how it is supposed to function. When the petrol leaks i take cap off and no difference. Its stopping me doi g long journeys. Does anybody have an idea what else could cause this... Bimmerforum threads helped me get thos beautiful car back on the road after my barn find here in New Zealand.....

[TedBobo]

The 1st post in this thread is likely the your problem. I had a similar issue with a puddle. After the tank was below a certain level....no more puddle. Replaced the pricey pump assembly about 10yrs ago, no more puddles or fuel smells.

[JDP530]

Just want to recap, i have had my 850i for a while now and it drives perfectly (usually) but i can only half fill the fuel tank otherwise i get a big puddle appear under the car. There is no tank pressure when i take the fuel cap off. I have jacked the car up and removed the vent valve blowing it through and it seems to work although i dont know exactly how it is supposed to function. When the petrol leaks i take cap off and no difference. Its stopping me doi g long journeys. Does anybody have an idea what else could cause this... Bimmerforum threads helped me get thos beautiful car back on the road after my barn find here in New Zealand.....

You may need to pull the right rear seat off and the cover over the tank so you can see if there's gas or residue on the cap where the pumps are installed. You may have to fill it back up again and check for leaks there on the top of fuel filter housing.

The vent valve under the right rear wheel well is a one-way valve to prevent gas spillage in the event that vehicle flips over.

[Willett1]

Thanks for that, it is only if filled over half way, and that is where it is coming out at the screw ring at the top of the pump, however, it must be back pressure into the tank from somewhere as there are no visible holes as such. I have replaced a regulator at the front, i do have two new filters to add when i get a chance but that shouldn't affect it, does the carbon cannister have anything to do with this perhaps.

[Mmrmm]

Apologies for waking up such an old post but, getting crazy here.

Changed fuel tubes, carbon filter, valve under rear wheel, etc.

Still get fuel smell, also got leaks when pressure is high.

Not sure how I can test the valve, if it should simply allow air into and out from the tank? That is not happening now. Does the car close or open any other valve to vent the system?

Would a vented fuel cap work here? Love my E31 but….

[raineycd]

Apologies for waking up such an old post but, getting crazy here.

Changed fuel tubes, carbon filter, valve under rear wheel, etc.

Still get fuel smell, also got leaks when pressure is high.

Not sure how I can test the valve, if it should simply allow air into and out from the tank? That is not happening now. Does the car close or open any other valve to vent the system?

Would a vented fuel cap work here? Love my E31 but….

When you open the fuel cap after it sits, does it expel air like it's pressurized? If so, probably still the valve in the rear wheel well or a line clogged.

[Mmrmm]

Can try to check that. What I noticed the last time was the following:

- car parked for a few months, tank almost empty
- no leaks, no smells
- first crank and it leaked, smelled a lot
- after a while it stopped leaking, smell was there of course

Before that, what I noticed a lot was that there were no smells on a first drive, but after a couple of hours parked when driving a second time on the same day the smell came back.

If “feels” somehow pressure related, not sure if into or out from the system. When parked no problems seem to exist. Only when fuel being pumped out….

Can’t make much sense out of this. Not sure:
- how to test the vent system (from where should I blow air, at what pressure it should flow, …)
- eventually how to bypass it completely (therefore my question about a vented fuel cap, I know some cars have it)

[cartoonz]

Fuel hoses at rear of engine will do what you describe

[Mmrmm]

Just bellow the microfilter you mean? Two very small curved tubes?

Done that.

[rogbmw]

Mmmmmmm. There are 4 lines there, not 2. 2 upper, 2 lower on the left driver's side.

[Mmrmm]

Really?

I think only the 2 small ones were done.

Will try and see if I can find those other 2!

[rjjablo]

Apologies for waking up such an old post but, getting crazy here.

Changed fuel tubes, carbon filter, valve under rear wheel, etc.

Still get fuel smell, also got leaks when pressure is high.

Not sure how I can test the valve, if it should simply allow air into and out from the tank? That is not happening now. Does the car close or open any other valve to vent the system?

Would a vented fuel cap work here? Love my E31 but….

I have been chasing fuel leaks this year again. I have previously replaced all the rubber fuel lines. However I did not use the Gates Barricade hose.

So the main culprits here are the two on the back on the engine. With the soft hose they were very suspectable to leaking and I spent a lot of time getting the line to the correct length so they would not bind and flex and leak. Also with the soft hose you had to clamp them hard and then the rubber starts tearing.

Other main culprits are on the fuel pump between the body and the tank. Pull your seats and look and if you see a puddle you either have a cracked fuel pump housing or bad hoses.