poss faulty fuel pump / relay

[ADE THE BLADE]

evening all...........will try and keep this brief. bear with me. ok, my partners fazer 600 has got a real bad fuel delivery issue in as much as if you whack the throttle open from idle it just splutters at best and at times stalls out ( no backfire ). i have checked everything and i mean everything to save you trying to guess probs and so its now down to the pump etc.

here we go....if i run a pipe from pump into empty bottle and connect pump directly to battery, it pumps fuel constantly all day long.

if i couple pump back up to main circuit, turn on key pump pushes fuel out into bottle ok for a count of `5` then relay shuts off ( or on ).

now this pump, apparently. has a back pressure sensor incorporated. if that is the case, why when i squeeze the pipe during the `5` count, the pump shuts off and when released ( to simulate low fuel at carbs.....calling for fuel, pump does not fire up. pipe from pump at that point is then completely empty.

so, after testing pump for resistance and relay for continuity ( both within spec ) is the pump on the blink (bearing in mind it seems to be running fine when tested remotely ) relay or possibly both ?

before anyone suggests trying to run a fuel supply remotely ( gravity feed ), this does not work as the fuel tap operates only via pump ( vacuum diagphram jobby ). even tried a drinks bottle with pipe directly down to fuel rail, bypassing even the fuel filter ! think that just ends up producing a nice big air lock down on the rail ..thats about it.....hope this info gives you enough insight to the problem.

please help as its the bosses bike and shes getting a bit ratty about it all cheers everyone in advance.

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