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Fuel Pump/Haynes Clarification

Posted: Fri Apr 10, 2009 11:32 am
by Davez29
Hi, due to a recent starting problem mentioned in an earlier thread I finally got around to cleaning my carbs, I did not think they were too bad but one of the inlet rubbers had not been installed correctly by the last owner and was allowing air to leak straight into the cylinder head. I am hoping that was my problem but Im waiting for a new rubber to arrive.

In the meantime I thought I would give my fuel pump a check. Now then the Haynes manual gives instruction that when the bike is turning over you should hear or feel the pump. Well remembering I aint got my carbs on I thought well at least I can try turning on the starter just to see if I can feel the pump, well nothing no noise or vibration, although the relay was giving a nice healthy click. Next I tried the test where you short the two wires coming from the relay, well the pump worked fine, gushing with petrol from what was left in the pipe and a nice loud pumping sound.

So my question is, has the bike got to be fully started to hear the pump or should I still hear/feel it while turning over via the starter? I just cant make my mind up while reading the Haynes manual Im not sure what it means for certain.

thanks for reading.

dave

Re: Fuel Pump/Haynes Clarification

Posted: Fri Apr 10, 2009 7:24 pm
by scratchin
im not 100% sure but i think the carbs need to be on the bike as the floats tell the pump when to send fuel

Re: Fuel Pump/Haynes Clarification

Posted: Fri Apr 10, 2009 10:06 pm
by Iccle
scratchin wrote:im not 100% sure but i think the carbs need to be on the bike as the floats tell the pump when to send fuel
I believe it to be the opposite; The pump will pump forever, until back pressure from the carbs "tells" it to stop.

Therefore, without Carbs, the pump should run forever... assuming you don't block off the outflow pipe, causing the required pressure to stop the pump, but it should run even when dry.

Re: Fuel Pump/Haynes Clarification

Posted: Sun Apr 12, 2009 8:42 pm
by Davez29
So, does this mean I should hear the pump while turning the bike on the starter without the carbs in place?