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Low power supply to MD50B2 high pressure fuel pump

Ian G

New member
I have been following an engine cranks but does not fire issue with my 50HP TLDI. I have dismantled the high pressure fuel pump & tested. Pump works fine & was clean with no corrosion. Reassembled & refitted. Checked spark & fuel. All good. Found only 3.8 volts DC at fuel pump when ignition is turned on. I would assume that the high pressure fuel pump should run when ignition is turned on. Can't access a circuit diagram to trace wiring to the source of the supply of if there is a pressure switch for the pump. Can anyone point me in the right direction? I am a HVAC tech with 50 + years behind me & have been playing & rebuilding all kinds of engines most of my life. This little Hi tech beastie won't beat me but it's got me stumped at the moment.
 
Of course diagrams are in the Factory service manual. I would suggest seeing whether you have a flaky ECU.
 
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