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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: BrickdUp on October 19, 2024, 01:49:19 PM

Title: Fuel pump runs indefinitely until cranked
Post by: BrickdUp on October 19, 2024, 01:49:19 PM

Hi all, new here, I have recently fitted a replacement fuel pump a few other items from a brand called quantum on my 1986 75S, after reasembling the system and testing that I’m infact getting fuel to the injectors I attempted to start, i then noticed that the fuel pump runs indefinitely until I crank the bike over, and then it stops, I cannot hear it running while I am cranking and when I let off the button after about a second it resumes, I can shut it off by using the killswitch on the bars or turning off the key, I have replaced the fuel pump as prior to this it would not run at all, may try refitting the original Bosch pump to see if I have rejigged something in the wiring and fixed the original issue, many thanks!

Title: Re: Fuel pump runs indefinitely until cranked
Post by: Ingo on October 20, 2024, 08:12:21 AM

So, with the pump working you should leave the pump for now and get into the wiring. There is a problem with power to the pump on while ignition is on but quits when engine turns over. This is a problem external to the pump. You'll need to get into the wiring, relays and switches...