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914World.com _ 914World Garage _ Fuel vent hose

Posted by: mgphoto Mar 27 2011, 11:30 PM

Hello,
I've had a problem with gasoline fumes coming into the cabin from the front trunk. I would fill the tank and sometimes forget and park the car at the curb, my street is pitched slightly from the center and slopes to the curbs, this makes the filler neck on the tank a few inches lower, this causes the fuel to run into the expansion tank. I wanted to replace the hose from the expansion tank as it has become brittle and cracked from age. I went to Bill and Steve's Superstore in Downey CA, to pick up a length of hose, ( they have thousands of VW parts ).
I spoke with Robert, who know exactly what hose I was taking about, "your getting the fuel fumes inside the car right?" yes I said, and he said "that is because the fuel is running through the hose", he told me to solve that problem "all you have to do is make a loop in the hose, and have the top of the loop higher that the filler neck."
See photos below.

Attached Image

Brilliant, the fuel will not run though the hose and the fumes are gone.
Just thought I would share this with the group.
Mike

Posted by: Tom_T Mar 27 2011, 11:47 PM

If the fuel vapor control system's hoses are all connected & not cracked/holed, the charcoal canister is not broken/cracked/rusted, & everything is properly run from the fan shroud/housing, up to the canister & filler neck, then back to the air filter on a stock EFI 914 to burn the fumes off in the engine - then you won't get the fumes at all.

If you're getting liquid fuel into the filler neck & expansion tank (i.e.: for fuel fumes expanding with heat of the day, etc.), then you probably either have a bad gasket in the fuel cap, or got yourself a vented cap - which was not OE on USA 914s. Since that cap looks nice-n-shiny, I'm guessing you recently bought one of those incorrect vented caps from the sellers online who don't know the stuff.

This is a fuel vapor control system - not a (liquid) fuel overflow control device.

Of course, if looping your vapor lines to prevent fuel flow which shouldn't be in there in the first place floats your boat - so be it!

PS Mike -

Note in the pix above that there is a "silver" solid drain line back into the tank from the overflow area to return the spilled fuel when you're filling up. So if you have a vented cap plus a blocked expansion system, it will force the expanding fuel up & out the vented cap & into that overflow catch basin to constantly evaporate & stink up the cockpit & trunk.

BTW - most all streets are "crowned" at the center & pitched (sloped) to the sides/curbs for drainage, so the cars have to be designed not to leak fuel when parked or driving on them, nor on banked turns.

More likely it's the heat while sitting out in the sun which is causing the fuel to expand more & faster when you park it on the street - as opposed to in the garage, then the leaking vented cap is having liquid fuel pool in the overflow basin on the opposite side of the solid drain line in your pix - sitting on the R/pass/curb side of that basin until evaporated or when you drive off & it's able to slosh back to the drain tube side.

Sorry, but IMHO ole Robert doesn't know WTF he's talking about in suggesting that fix, and clearly does NOT understand the 914s' fuel and vapor control systems!

Posted by: jaxdream Mar 28 2011, 07:16 AM

Having the right cap won't keep the fuel from sloshing / running up into that little hose , then into the expansion tank . But the loop in the hose with the loop above the fill level will , as mgphoto has already said it helped his problem . That's the reason there are P traps put into plumbing of houses , to keep the sewer vapor ( smell ) from coming back inside the house . Heck I like that idea , it's cheap , and seems to be effective .
My $.02

Jack / Jaxdream