[xj] Fuel return valve

I have just fitted a new l.h. fuel return valve, but the
darn thing appears to leak. From what I can work out, 12 v
is applied to the l.h. solonoid when the r.h. tank is
selected, causing the valve to close and preventing fuel
returning to the l.h. tank. With the car running and the
r.h. tank selected, there is a good flow of fuel back to the
r.h. tank as desired. But there is also a dribble of fuel
to the l.h. tank. I discovered this after a day’s drive
using the r.h. tank all the way and found the l.h.
overflowing when I got home.

Today I removed the new l.h. valve again and checked it out.
With 12 v applied to the terminals, the valve closes so you
can’t blow through it. With 0 v it opens and you can blow
through. So far so good, but when the fuel return line is
connected, r.h. tank selected and the car run, fuel dribbles
out.

And so to my question - It does seem like there might be a
bit of crud in the seat. I’m tempted to blow some
compressed air through the valve. Is this o.k, or is it
likely to damage the valve?

Cheers & thanks–
Bill '80 XJ Ser III 4.2
Brisbane/Qld, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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Hooksie wrote:

I have just fitted a new l.h. fuel return valve, but the
darn thing appears to leak…
…Today I removed the new l.h. valve again and checked it out.
With 12 v applied to the terminals, the valve closes so you
can’t blow through it. With 0 v it opens and you can blow
through. So far so good, but when the fuel return line is
connected, r.h. tank selected and the car run, fuel dribbles
out.

Are you sure that the power to the valve, when mounted in the car, is
reaching the valve, Bill…?

As tested outside, if you cannot blow though it is properly closed then

  • and there is no reason why it should leak in car. The returned petrol
    has nominally no pressure after passing through the pressure regulator.

Hypothetically; the ‘right’ valve may no open fully, causing rising
system pressure as lots of fuel is passed by the regulator. This will
interfere with pressure regulator operation, causing unwanted rising
fuel rail pressure.

However; a valve may be subjected to very high pressure, like if the
regulator fails - and is meant to stand that. So using compressed air
with some care, not excessive and through an open valve, should be
‘safe’ - though a new valve should not have crudded seats…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)>And so to my question - It does seem like there might be a

bit of crud in the seat. I’m tempted to blow some
compressed air through the valve. Is this o.k, or is it
likely to damage the valve?

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
Archives: http://www.jag-lovers.org/lists/search.html

To remove yourself from this list, go to http://www.jag-lovers.org/cgi-bin/majordomo.

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