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Thread: Fuel Pump Issue

  1. #1
    SOC Member SwissSteve's Avatar
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    Fuel Pump Issue

    Last week I tried to start the car after a layup since last October.
    Initially the car started then died after a minute or so. Checked and
    there was no fuel at the filter in the engine bay. The pump was ticking
    but normally after a few secends the ticking would slow down and stop. Now
    it is just ticking continues.

    Took the banjo bolt from the top out connector on the pump and no fuel at
    the output of the pump. Took off the inlet and blew into the pipe and there is no
    blockage as I could hear the fuel bubbling in the tanp (tank is half full). Checked
    also the output pipe and could blow also so assume the pipes are clear. Thought at
    this point a problem with the fuel pump.

    Order a SU fuel Pump this week and fitted it today. On switching on the ignition no
    clicking and no fuel being pumped. Assume at this point i have a faulty new pump.

    So moved back to the old fuel pump and checked that the solonoid piston is working fine.
    So tried to fix the old pump with the new pump parts as the solonoid is working and I
    can hear the pump ticking.

    Changed the diaphram and the inpet and outlet assemblies and confirmed they are fitted
    in accordance with the manuel. Also fitted a new peice of pipe from the tank to the banjo
    inlet. Still nothing.

    Finally I took of the Banjo connectors and could feel slick sucking and pushing from
    the pump.

    Not sure what to do next. Is there still an issue with the old pump? I assume as I can hear
    nothing with the new pump no ticking I assume this is a fault unit.

    Anyone any ideas what to try next?

  2. #2
    Senior Member
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    I have had a pump tick but not pump, and it was due to a bit of debris in the pump inlet valve - it was holding the inlet valve open, so the fuel just kept going back and forth from tank to pump but didn't make it past the pump chamber and out towards the engine

    But as you have stripped the pump, are you sure you have the valve assemblies right? Try getting a bit of pipe and see if you can blow into the pump inlet and not be able to suck back, and the opposite on the outlet side - you should be able to suck air through but not blow back into the pump.

    If your pipe to the front is genuinely clear, and the tank line is too, with fuel, it can only be the pump, and therefore you need to recheck your repair work - including, if you have been playing, the pump throw is correct (I have the proper SU manual that covers these adjustments if you need the procedure)
    Last edited by kryten; 12th August 2017 at 16:24.

  3. #3
    SOC Member SwissSteve's Avatar
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    Quote Originally Posted by kryten View Post
    I have had a pump tick but not pump, and it was due to a bit of debris in the pump inlet valve - it was holding the inlet valve open, so the fuel just kept going back and forth from tank to pump but didn't make it past the pump chamber and out towards the engine

    But as you have stripped the pump, are you sure you have the valve assemblies right? Try getting a bit of pipe and see if you can blow into the pump inlet and not be able to suck back, and the opposite on the outlet side - you should be able to suck air through but not blow back into the pump.

    If your pipe to the front is genuinely clear, and the tank line is too, with fuel, it can only be the pump, and therefore you need to recheck your repair work - including, if you have been playing, the pump throw is correct (I have the proper SU manual that covers these adjustments if you need the procedure)
    Tried the suck / bow test and the blow was quite free. Sucking however was not solidly blocked.
    Will take it apart again tomorrow and have a look if I have missed something

  4. #4
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    Worth dribbling a little fuel into the pump to wet the valves and prime it a bit

  5. #5
    SOC Member SwissSteve's Avatar
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    Quote Originally Posted by kryten View Post
    Worth dribbling a little fuel into the pump to wet the valves and prime it a bit
    Priming the pump did the trick on the old pump but not how I expected it.
    The fuel on the inlet side dripped straight onto my feet :-(

    The cork seal inside the Reservoir cap on the fuel pump was not air tight and leaking.
    Once I fixed that the old pump came back to like and the old pump is now working fine.

    Thx for the tip Ken

  6. #6
    Senior Member
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    No problem - 40+ years of playing with these things gives you loads of things to try.

    Glad it worked

    Russ

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