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Thread: Failing Fuel Pump R1100RS

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  1. #1

    Failing Fuel Pump R1100RS

    Seeking guidance on possible fuel pump failure on the '94 Oilhead. Has been dif' to start recently and when it would start the exhaust was noticeable of smelling of gas. Won't start now, fuel pump not heard pressurizing when ignition key switched to start position. Checked fuse and swapped out relay under seat but still no fuel pump action. Pin connectors secured. So it would seem that the Fuel Pump had died but first before I lay down heavy dollars by ordering a replacement I am woundering it there is a way that I can readily check the fault being at the pump, any other guidance will be appreciated, thx! Bill

  2. #2
    Registered User roger 04 rt's Avatar
    Join Date
    Oct 2011
    Florida & Massachusetts
    Remove the fuel pump relay and jumper pin 3 to pin 5. The pump should immediately come to life.

    You could also try separating the fuel tank connector and reseating it a few times.

  3. #3
    Remove the fuel pump relay and jumper pin 3 to pin 5. The pump should immediately come to life.

    You could also try separating the fuel tank connector and reseating it a few times.[/QUOTE]

  4. #4

    RE: R1100RS possible fuel pump failure

    Thx for the response. I had removed the F.P. Relay and used known good alternate relay in its place, still nothing coming to life concerning audible pressuring up from the pump, conclusion is that the original relay should be good. #6 push-fuse is also good. When place the ignition on the start position I ear a subtle click from the relay bank this also suggest the relay is good? Disconnected/reconnected the harness from gas-tank to relay connection. If I've completed a thorough tracing of problem areas then yes of course the pump must be bad but there may be more to consider looking at then I know so picking out the info' from you peoples. One additional question is concerning micro-fiches showing 2 fuel pumps, one being a "Suppressed" pump and the other pump is simply referred as a Fuel Pump. Which one is the correct for the '94 and then also how many M.M. is my correct size? I see that there are several of different M.M. sizes for example a 37mm and a 43mm?

  5. #5
    Registered User
    Join Date
    Jul 2017
    Bunbury WA Australia
    If you do the test Roger suggests, that will test the whole circuit EXCEPT the relay control section. It will give you alot of information to help solve your problem.
    As well as re-seating the Fuel pump/gauge connector, to try to improve electrical conductivity, you could jump 12v directly to pump side of the plug and see if the pump fires up then. ( Be careful you get the right terminals. )

  6. #6
    I am sure somebody can help me out here, but how in the world would a "failing" fuel pump - either not pumping or pumping at less than robust - cause a rich condition and the smell of excess fuel.

    I think we have either a fuel pressure regulator issue (very rare) or an intermittent spark issue causing incomplete combustion.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell

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