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Re: noise from fuel pump running



Does anyone out there know how the fuel delivery system works on the ST.  I hear the pump turn on with the ignition, then "charge" the system, and then shut off.  Kind of coolJust guessing, but is the pump controlled by a pressure switch, with the system dampened by an accumultor of some sort.   If the pump is a positive displacement type pump, then the system must be protected by some kind of mechanical relief valve (normally closed) which will "dump" excess pressure either back to the pump suction or back to the tank.  Otherwise a blockage of flow will stop the pump completely while energized.  Sniff Sniff I smell something burning :)   If all of this is true, then a continuously running pump may be caused by a malfunction with either the pressure switch, or the relief valve is stuck open, resulting in cut-out pressure never being established.  Maybe a tank venting problem resulting in restricted suction flow, causing the pump to cavitate??   Any other opinions/facts...maybe its a centrifugal pump which would need a restricted recirculation path instead of a relief valve?,   I have not a clue?  I need to get one of those full shop manuals and the nifty microfiche files!!!!  Curiocity kills the cat.


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