Lou Danzico personal wrote:
With regard to the bleed down. I placed the pressure gauge in place of the then malfunctioning carburetor. While running the pump, I saw no leaks, but did not look in the boot. I can do a more restricted test next week, removing the second carburetor from the line and even put the gauge in right after the pump. Assuming there is no other leaks, could fuel be leaking back through the pump? I assume thee some seals in there? I’ve never disassembled a pump. The one in question is an after market unit purchased perhaps 20 years ago. It’s plastic outside and of questionable quality. The other is original.
It’s a question of whether or not the pump is of a type that is meant to
stop as pressure is reached, Lou, which then should be maintained
without the pump running - or if it is sort of continuous…
In the former case; continuous pumping is a fault, of course, but very
little fuel is involved - so even a tiny leak will restart the pump
pretty pronto. As long as the leak is not external, fire hazard, or
internal in the carb, causing excessive float levels - it’s ‘benign’…
It may indeed be the pump itself that is leaking internally, but as long
as it delivers properly to the carb(s) it’s of little concern. The pump
is basically meant to stand continuous running - which it has to as long
as the engine is running anyway. Connecting the gauge directly to the
pump will eliminate all but the pump’s internals…
The compression stated should not in itself cause abnormally low vacuum
- bt a recheck is of course in order…
xj6 85 Sov Euroep (UK/NZ)>On the compression, the last time I checked, there was one or two cylinders at 125 and the others at about 135. Will check next week.
On Feb 11, 2012, at 10:26 PM, Frank Andersen wrote:
Lou Danzico personal wrote:
I installed a Grosse Jet needle valve in the carburetor and that did the trick. No more leaks.
I also checked the fuel pressure at the carburetor inlet and it was 6 PSIG at each push of the pump, dropping to 5.5, and then another push to 6, and so on.
That’s just dandy pressures, Lou - but, depending on pump type; it should stop as it reaches its set pressure. With that type a continuous pumping indicates a bleed-down…?
And as I’m facing an inexlicable low vacuum myself, not in your league, but low - I’m interested in what you find. I have injection, so it may not be comparable - but I do have 140 psi compression, give or take a tad on all cylinders…
I started the car, and quickly shut it off, turned out the lights and left before anything else could go wrong.
Next week I will do a dry and wet compression test in regard to low vacuum.
The archives and FAQ will answer many queries on the XJ series…
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