[T3] Sputtering on hills and uneven fuel at speed

Jim Adney jadney at vwtype3.org
Wed Oct 1 20:18:42 PDT 2014

On 1 Oct 2014 at 11:45, Chris Sheridan wrote:

> Drove it home last night and noticed some unusual behavior -
> at highway speeds my gas foot was steady, but her speed was fluctuating
> about about 10mph here and there. You could feel and hear it increasing and
> decreasing slightly while at highway speeds. This morning started up fine
> as usual but climbing up the big hill to my kids school immediately hit
> major sputtering and coughing. ground leveled out and she was ok again,
> more or less. 

There are many possibilities for something like this, but my first 
thought is that it appears that you're okay until the engine gets 
loaded a bit more. The first thing I would check would be the fuel 
filter. Pull off the input hose to the pump. You should get a pencil 
sized, scary amount of gas pouring out. If it's just a trickle, 
something upstream is blocking the free flow of gas. That would 
typically be the inline filter or the filter screen in the tank. Pull 
the hose off the inlet side of the filter to see if you get good flow 

Have you installed one of my overflow hose kits? If not, it's almost 
certain that you have water and dirt in your tank and this is what's 
blocking your filter. Wheel spray throws those into the cracks in the 
overflow hose when you drive. The filter has a paper element which 
soaks up water and then refuses to let gas thru. If you think this 
might be your problem, drain a bunch of gas out before you install a 
new filter. If you use a glass container (carefully!) you will be 
able to see water settling in the bottom of the container. You can 
pour off and reuse that gas once the water has all settled out.  

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

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