inline fuel pump

[welly_59]

would it be possible to fit an uprated inline fuel pump instead of changing the one in the tank? reason being is there's one for sale on imoc at the moment! if it works it might be easier thank dropping the tank

[nik]

this has been done in the USA yes..i asked this question once on mr2oc and was told you can fit an inline pump and just pull through the internal tank pump..

[Goldy]

Does that really work? I thought u could only suck as hard as the other pump can blow (if you get my drift) O:)

[superchargedsam]

Yeah I thought same as goldy surely this will put pressure on the inline pump to try and suck harder than the fuel is being delivered ! would it not be better to just leave the in tank pump out of the equation all together, all my bikes use gravity feed so nothing to bottle neck the fuel there which is how I see the in tank pump in this set up ! must be a reason why and how this works !

[nik]

my understanding was that the in tank pump is not wired up..so its just a dead pump and the in-line pulls through that..

[superchargedsam]

ah if thats the case Nik then I understand but the way it says on IMOC is the intank pump supplies fuel at low pressure then the inline feeds it at high pressure but if its not wired for intank that explains it !

[welly_59]

lol all this seems confusing, maybe it would just be easier to change the pump in the tank after all....

[djdna2000]

The flow of any pump is rated at the pressure it is designed to output, or if you like the pressure it is designed to pump into. So if your base fuel pressure is say 40 psi at the rail, your pump will be rated at say 110 litres per hour at 40 psi. If you increase the rail pressure (e.g. using an adjustable fuel pressure regulator to get more flow from your injectors) then your pump will only be able to supply less fuel into that pressure, e.g. 110 lph @ 40 psi, but only 90 lph @ 50 psi.

However if you now fit a powerful pump further upstream from the in-tank pump, this is now changing the pressure that your in-tank pump is trying to pump into. Instead of pumping into 40 psi, it may be 0 psi or even less, so the flow rating of the pump is vastly increased. The pumps 'in series' help each other out.

[superchargedsam]

Dan knew there would be a simple explanation for this :-\" that does make plenty of sense and does it explain it very easily cheers fella.