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Re: [T3] FI fuel pump problems

I've got a fuel pump which spins, but doesn't put out
any flow or 
pressure. There actually IS flow out the overflow
line, but not out the output 
line. And even when I pinch off the overflow line I
don't get any output.

This is driving me nuts, because the problem comes and
goes, so 
sometimes I think it's "fixed" even though I don't
know what I did to fix it.

Now I've had the pump head apart and everything that I
can see appears 
to be okay. I have NOT taken the little crimped cap
apart, however, so I'm 
wondering if the rubber tip of the check valve has
come loose from the plunger. I 
don't know if I've ever seen what this is supposed to
look like inside, but I 
can see the end of the plunger by prying it back with
a small screwdriver. 

What I see looks rather long, thin, and pointy, maybe
3mm dia and 6mm 
long. Is that just a central mounting spike for the
real rubber seal?

I'm trying to avoid removing the crimped cover on
those springs and 
valves, because I'm not sure I can crimp it again

If this starts to become a problem, I think I'd like
to come up with a 
fix that just removes the check valve function from
the pump body and 
substitutes a separate in-line check valve. Anyone
know of a supplier of inexpensive 
5/16" in-line check valves that would be compatable
with gasoline?

Your check valve has died.  I've had a couple of pumps
do that.  I don't know the measurements and
tolerances, but I suspect that the gap around the
piston has gotten too large so now there is too much
leak-by for the plunger to be forced back. There's a
bronze-looking sleeve in there, but I don't know if it
could be successfully replaced.

I was able to successfully revive one pump by removing
the cap  and cutting a coil off of the spring. That
softened it up just enough to start working again. 
Had another that just wouldn't go so I cut a small
plug that holds the plunger in the normal output
position.  The pump now pumps and relieves fine, but
has no check valve function.  The plug fits in the
little alcove at the end of the flow channel.

The cap is not hard at all to crimp back (just don't
let the spring get away).  I just used a screwdriver
with a tip of appropriate width, and pressed it in
with finger pressure.  That cap is paper thin, but it
has a nice rubber seal underneath so tightness isn't a

I've considered adding an inline check valve, but the
primer switch trick accomplishes the same thing so I'm
not sure it's worth the effort to hunt one down.

'70 Clementine Fasty (in progress)

List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org

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