[T3] Fuel leak on type 3 F.I. Fastback

Jim Adney jadney at vwtype3.org
Tue Nov 5 05:54:39 PST 2019

On 4 Nov 2019 at 10:25, Arthur Sterrett wrote:

> My fastback has developed a fuel leak which appears to be coming from in the
> tunnel!

It's most likely that the steel lines are fine, but there's a leak at 
the hose connection at one end which is dribbling/spraying back into 
the inside of the car. Check the driver's side first, as the 
pressurized line is more likely to be the problem.  

Those 4 connections are more troublesome because the steel tubes 
there do not have barbs or bulges on them, which would help seal the 
hoses. The straight cylindrical tube needs a full circle clamp and 
the usual worm gear hose clamp doesn't do that job; it leaves a loose 
spot at each end of the "buckle" where they tend to leak.  

At those 4 spots, use either a special FI clamp, available at your 
FLAPS, or one of the plastic click/ratchet clamps. Those all do a 
good job. I use a standard (small diameter) worm gear clamp to grip 
the hose on the tube plus a plastic click/ratchet clamp to give full 
circle sealing.  

Another possibility is that what you're seeing is not gas, but brake 
fluid. The usual failure modes for our brake system is a master 
cylinder that is leaking out the mouth or the line under the gas 
pedal that has rusted thru and sprays out each time you press on the 

Brake fluid mixes completely with plain water; gas does not.  

If you're sure it's a rusted out gas tube, you could try compressed 
air to see which one leaks, but that means disconnecting the hoses on 
both ends so you can seal up the tube and leak test it alone.  

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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