Sunday, December 22, 2024 8:47:08 AM

3 litre mechanical fuel pump

11 years ago
#2442 Quote
Does anyone know what the thread size of the brass unions on the mchanical fuel pump are? The one on the inlet side of mine has split longitudinally and is sucking air so I need to replace them.  Andrew Posted by tf1695 26/02/2013 19:37:02
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11 years ago
#2443 Quote
I believe the thread profile is BSP not sure of the size. maybe 5/16 or 3/8. The usual sources will have a replacement or try a gas fitter or a yacht chandlers for a shiney new one. Posted by Peter Martin 27/02/2013 08:56:04
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11 years ago
#2444 Quote
The threads in the AC pump body appear close to, but may not be bsp.  On my car they seem to be UNF 1/2" - 20, JIC cone. Also the same on a spare fuel pump body.  The cone seals the connection into the pump body (no use of tape or sealants).  The fitting will most likely be made for 5/16" copper pipe. In this case it would be a brass 1/2" UNF-20 JIC to 5/16" pipe fitting.  The present fuel inlet-pipe is probably attached with a nut + compression olive. The nut thread may depend on the make of fitting. It is possibly neither bsp or UNF. Overtightening of the nut can be the cause of the split fitting.  If the inlet-fitting is replaced, then the nut and olive should be replaced with it as the old olive will be work hardened and probably distorted.  Measure the diameter of the existing copper pipe, probably 5/16", and that will dictate the fitting you need. The new fitting will come with nut and olive (If the pipe is long enough, carefully cut the old olive off the pipe to install the new nut + olive, and be sure to lubricate the back face of the new olive when tightening the nut to compress the new olive on to the existing pipe).  In case you want to change the fuel-pipe at the same time, a new one can be obtained from Chris Prince. Then you can match the nut on the new line with the fitting that you get.  An adapter fitting is also available from hydraulics suppliers, 1/2" UNF-20 JIC for the pump inlet, with a 1/4" bsp male (coned internally) for the fuel-supply connection. Then you may attach a standard (brass) 1/4" bsp nut and tail with a short flexible fuel hose on to the original copper pipe.  Hope this helps Posted by lacey giles 27/02/2013 11:02:29
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