Hello
Not sure on the working of the fuel pump… is it suppose to run when you turn the ignition on? Does it switch off when the fuel bowls are full? any advise on the understanding would be great. Thank you
The fuel pump only runs while the ignition is on and the engine is turning either by the starter or under its own power.The operation of the pump can be tested by unplugging the pump relay located next to the regulator rectifier and connecting the black and white terminals with a piece of wire and turning the ignition on.The pump should then run until the float chambers are full
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My 86’ R’s pump comes on with only the ignition, without the engine running or turning over. Has it been modified?
Thanks,
Gil
Does the pump stop once the float bowls are full..??
Smithy.
Well, kind of, it’s like an on demand water pump like one might find in an rv. If the bowls are empty it’ll pump rapidly for a few seconds and as the bowls fill it slows to a stop.
That’s a bit strange….normally the pump will run only once the engine is either turning over or running….not just with the ignition on.
I wonder if it has been “by-passed” as per Bif’s reply above.
Smithy.
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Hi lowflyer, If the pump comes on with just the ignition the fuel pump relay has been by passed as bif says, its not that unusual, ive had so many issues with fuel pump relays in the past that I always remove it and bypass..
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Thanks for info people 
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Thanks, Bif, Pete, and Smithy.
So, no issues with it configured as it is? Just let it ride?
Gil
Shouldn’t be an issue…when riding at a reasonable speed, the pump is essentially constantly running anyway to keep the float bowls full. The pump itself has a “pressure switch” of sorts in one end, when the fuel pressure reaches a certain level, (very low, only a couple of psi), the pump will stop until the fuel level in the float bowls lower and allow the needles/seat to open, this then lowers the fuel line pressure and the pump will start again…very simple and quite effective. Some people actually do away with the pump alltogether and just run gravity feed…this works fine until the fuel level in the tank gets very low…you’ll notice the lowest part of the tank is very close to the float bowl level…then the fuel will struggle to gravity feed. I ran gravity feed on several of my VF’s back in the day when the pump died…I just had to remember to not let the level in the tank get too low.
Smithy.
I think the main issue with this set up is that if the bike tips over or you crash the engine may or may not stop running but the fuel will keep flowing…
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Good thought Don. I hadn’t actually thought too much about it….maybe I should in future.
I suspect most of the time if the bike crashes or falls over the engine will stop due to the float bowls emptying themselves through the vents…and if the fuel pump is wired normally it will stop pumping when the engine stops running…by-passing the pump will have it pumping all the time the ignition is on….can make a bad day much worse.
Smithy.