Fuel leak under rear seat onto pavement

[thomash85715]

Hi: My 82 320i has suddenly started drip drip dripping when the engine is running from the passenger side about 2/3 of the way back. It appears to be coming from a rubber hose that is attached to top of the fuel tank. Haynes manual states access can be had by removing rear seat cushion and a cover plate. Has anyone ever done this? Just want to make sure this will be a fruitful enterprise. Thank you. --Tom in AZ

[shogun]

Have a look here under fuel supply at the drawings http://www.realoem.com/bmw/enUS/part...2-E21-BMW-320i

[Mike2002]

Did you just top off your fuel tank? If so, it could be your vent lines are cracked. If this is the case, it will stop dripping when the fuel level goes down below the vent.

[Bimmerknut]

This is common with fuel hoses in our older cars. Two screws hold the seats in. Remove them and then lift the back of the seats off of the hook the holds them in place. They're a little tricky. It could be the main supply hose, the hose between the two tanks, or any of them. Also dropping the tanks is pretty easy. It's tight in there though, and everything is old. Be careful pulling hoses and wires.

[epmedia]

Don't drive the car until you get it fixed.

And be safe with fuel. Have someone get a fire extinguisher for you too.

[thomash85715]

Wow these are helpful. Thank you. I am having trouble determining which drawing is the one for my car though. There are some differences among them. I will go ahead and pull the rear seat out and try to get the top of the right side tank exposed.

[Tom D]

you really just need to drop the tanks and replace all the non-metal fuel and vent lines. most of them if I remember correctly are 12mm and 14mm, you can subsitute with 1/2 and 5/8. this is a known problem and has been discussed many times, a search should bring up a tread or two and it might even be in the FAQ.

[SilverPuddle]

Following is a link to a thread:
http://www.bimmerforums.com/forum/sh...9#post15184829

[Hagbard]

Also check the o-ring gasket under your in-tank fuel pump. It can wear out and cause fuel to leak from the top of the fuel tank when you fill up.

[thomash85715]

Turns out to be a pinhole in the line leaving the filter and coupling to a metal line accessible through the under-seat portal. Ordered from dealer for $38; four day delay. Only scary part is making sure pressure is zero before undoing fittings. Book says start engine and remove relay, then crank for a while. Can't I just remove relay, then crank for a while? How long is a while? Thank you for all the help.

[epmedia]

Turns out to be a pinhole in the line leaving the filter and coupling to a metal line accessible through the under-seat portal. Ordered from dealer for $38; four day delay. Only scary part is making sure pressure is zero before undoing fittings. Book says start engine and remove relay, then crank for a while. Can't I just remove relay, then crank for a while? How long is a while? Thank you for all the help.

The hose from the filter to the hard line is the high pressure side of the fuel system. If it has a pinhole leak on it, there wont be but very little residual pressure on it within just several minutes. Because you have a leak, there is no reason to start the engine and then remove the fuel pump fuse/relay.

Not only that, but running the engine and pulling the fuel pump fuse(or relay) will only reduce the pressure from ~75psi to ~44 psi. It's safest to just wait a few hours before opening the pressure side of the fuel system.

Get some eye protection and a fire extinguisher. Never open a fuel system without these two items. No sparks allowed.

That hardline that connects to the flex hose is going to be difficult to work with. I suggest soaking the fittings with penetrant several times while waiting for your new hose. And only use quality tools, otherwise you could mess up the fittings.

Please take pics of your progress for us, especially if you have questions or run into trouble.

[Thecatmilton]

My $300 320i does this. I drove it around today for awhile and noticed it when I got back.

[320iAman]

That hose is prone to leak as it ages. Disconnect the negative battery terminal, The hose will have a little gas in it, the fuel filter is where a cup or or two of gasoline is,,put a pan underneath before unscrewing the banjo bolt holding the hose to the fuel filter. Righty tighty, lefty loosee... I think its a 22mm open end wrench holds the fuel filter and 19 mm wrench unscrews the banjo bolt by opposite twisting of each and the vice versa or reverse to screw it in with copper sealing rings.

Randy

[dumbclub]

Here's what you'll find under the access cover after removing the rear seat:



The gold colored thing in the middle is the in-tank fuel pump and fuel level sending unit (#13 and #9 below). It extends down into the right side fuel tank and has an O-ring seal (#12) that should be checked. All of those cloth covered rubber fuel lines will need to be replaced, but you'll need to drop the tanks (#1 and #2) to get to them. Be sure to follow Robert's (epmedia) precautions while you're doing this.




Also check the large hose (#17) that connects the tanks for cracking at the connection points. It probably needs to be replaced too.





All of these vent hoses and maybe the plastic "Y" and "T" connectors (#5 and #6) will probably need to be replaced. Pull it all apart and take an inventory of the sizes and lengths you need before heading to the parts store. The plastic connectors should be ordered from a dealer ahead of time. All of that should fix the leak you have now and prevent new problems well into the future.

While you've got it all apart, consider cleaning and coating the inside of your fuel tanks with a sealer. There's bound to be a lot of crud in them.

[thomash85715]

Hi: I am the person who started this thread. I could not get the main high pressure fittings loosened so I drove to my local hot rod guy with gas dripping the whole two miles. I provided him the new line and filter which he put on for not much $$$. He told me had to drop the tanks to get the new hose through its little "tunnel" due to an old clamp being jammed in there by a previous owner or repair person. He surmised the loose clamp strafed on the hose and caused it to fail. One of those things we will never know. Sorry I have no images but the great one on here showing the area under the secret cover look just like my car.
Also, I ended up with a made in taiwan filter after rejecting the Wix one offered me by a local parts house. The box said "contents made in USA" but the outer can was stamped Made in china. OReilly house brand was less than half the cost of the Wix chinese one. The guy trying to sell me the chinese one stated: "Just cos it says made in china does not mean it's bad."

[epmedia]

Sounds like maybe a cheap knock-off was put in WIX box. I have 2 WIX fuel filers that say made in W. Germany.
Edit: actually they are in a WIX package, but the brand stamped on the filter is KYS (Kayser) made in W. Germany.

Did your tech replace any of the fuel vent hoses while under there? If not, expect to need doing that soon if none of the original vent hoses(cloth braided) have been replaced.