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« on: April 10, 2021, 12:49:55 AM »
450 psi would be considered fairly "normal" although this is not a spec nor a procedure proferred by Lister for these machines. We sometimes get down to this if we have a balking engine that we cannot get an accurate diagnosis from the usual crankcase vacuum measurement. (i.e. the engine just cannot be started). What you are actually looking for is consistent even compression across all cylinders. 350 psi may be considered enough on one of these very small engines. You cannot test through an injector. Use an adapter made for the purpose.
Injectors should be bench tested for pop pressure, spray pattern, seal and consistency across cylinders. They can be installed inverted onto your engine if you want to confirm fuel pump operation as well, just cannot see as many details when doing it that way.
The leak-off line from top of injector allows the system to be somewhat self-purging of air in the lines. With a new tight perfect injector there may be no fuel bypass at all... with others there may be considerable, but that generally means that there is internal leakage within the injector body. Some CS models actually used a small open container to catch the very slight drip from the injector leak-off. Newer fuel systems route this back into the fuel supply tank or back into the secondary fuel filter as in your SR.
dieselgman