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Post by roy0147 on Jul 13, 2021 17:45:53 GMT
I would be grateful if someone could try and help me please with an annoying problem. One of the float chambers is not shutting off and petrol is overflowing from the overflow pipe at the top of the lid. I have checked and the float is not punctured. The hinged lever moves freely and the shut off needle also moves freely. With the top assembly off I can blow through the inlet through the filter and by pressing the hinged lever stops me blowing so I assumed that it is working. When assembled however the petrol level rises and comes out of the overflow pipe again. I have tried bending the lever to a 12mm bar as recommended for a metal float type. This is annoying and I must be missing something and do not know what to replace or what else to do so any ideas would be welcome. I will try to upload a couple of photos to show the lever down and then up as if the petrol level was correct. Thank you in advance. Attachments:
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Post by canuck on Jul 13, 2021 18:52:12 GMT
Hello Roy, These needle valves can be a test. Is the needle valve rubber tipped or metal tipped? The rubber tipped can perish and the metal tipped can compress and damage the seat. The correct height setting is a 7/16" round bar with valve needle at horizontal. Verify the fuel pump pressure is not greater than 3 psi. Bruce
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Post by roy0147 on Jul 13, 2021 19:23:01 GMT
Thanks Bruce, The needle has a metal tip and when I blow hard into the inlet port air will flow and stop when I close the valve with the lever so I didn't think that was the problem.
I did try bending the lever as shown in the workshop manual to the 7/16 bar. I am not sure how to test the pressure from the pump though. I couldn't unscrew the needle body from the top as I was going to try a new needle and seat. I seem to have a silly problem!
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Post by ozieagle on Jul 13, 2021 21:41:14 GMT
Hi Roy
As Bruce said.
I would be 90% confident that your needle valve and seat are shot. I use a 9mm 1/4" drive socket to remove them. Not a perfect fit but do the job.
If you have an SU fuel pump, it will automatically be the correct pressure. All bets are off, with an after market pump. You will need a fuel pressure gauge, to check.
The pressure on the needle valve is very small, and I think you pushing it closed is a much higher pressure than the petrol exerts, which is why it seals.
Herb
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Post by roy0147 on Jul 14, 2021 7:26:56 GMT
Thank you Herb, I have just managed to remove my needle valve with a 9mm socket - it was a really tight fit but after 60 years perhaps not surprising. I have ordered a new valve from Riley Spares and hope that this may solve my problems. Looking in the boot I can see that a new pump has been fitted with the name FACET so I don't know if this gives 3 p.s.i. Cheers
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Post by canuck on Jul 14, 2021 19:42:00 GMT
Hello Roy Yes I concur a new fuel valve should see you good. If a Facet cube type, (below) or a cylindrical type for that matter the model number will be found on the metal mounting tab where the bolt goes through. Check this number against the Facet model listing to determine the pressure of the pump. Bruce
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Post by ozieagle on Jul 16, 2021 21:56:24 GMT
As Bruce said, some Facets are OK with our cars. They are listed as 2-4psi. One downside to them is that they are NOISY, rattling away continuously. They need to be mounted with noise insulating rubbers. I have used grommets in the mounting holes.
Herb
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Post by roy0147 on Aug 2, 2021 17:04:57 GMT
Thank you for all of your help. I have now replaced the needle valve and seat and now there are no petrol leaks! I did notice that my Facet pump (which is rated at 3psi) does not shut off when the SU float chambers are full but keeps on ticking away but Herb says they 'rattle away continuously' so I assume mine is working normally. The old SU pumps used to cut off if my memory is correct. I can now continue the remedial work on the brake cylinders, ignition circuit, electrics etc.
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Post by ozieagle on Aug 4, 2021 0:49:25 GMT
Glad you leak is sorted.
Yes Facets, and other similar pumps, run all the time. With SUs, they stop when the back pressure stops the diaphragm moving with spring pressure. The Facet has an internal bypass, hence the continuous running.
Herb
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Post by canuck on Aug 11, 2021 16:10:05 GMT
Thank you for all of your help. I have now replaced the needle valve and seat and now there are no petrol leaks! I did notice that my Facet pump (which is rated at 3psi) does not shut off when the SU float chambers are full but keeps on ticking away but Herb says they 'rattle away continuously' so I assume mine is working normally. The old SU pumps used to cut off if my memory is correct. I can now continue the remedial work on the brake cylinders, ignition circuit, electrics etc. Hello Roy, Nice to read you have the fuel issue sorted. You can mitigate the annoying constant clatter by using the purpose for facet mounts. The mounts are part of a kit that includes a wire lead, and allows the Facet pump to be installed on a Positive earth car as most of ours still are. Salut Bruce
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