pewe
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| posted on 28/5/09 at 09:51 AM |
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Fuel Pumps
The external Bosch fuel pump, which was new about 1500 miles ago, seems to be groaning and moaning even with a good amount of fuel in the tank.
Bosch Technical reckon that ideally all external pumps should be gravity fed i.e. situated below the tank outlet as they are designed to blow not
suck.
I thought I'd overcome this by fitting a non-return valve upstream of the pump but it seems that hasn't been enough.
One thought is to fit a lift pump in the tank - seems a bit extreme to me.
Any thoughts/advice please?
Cheers, Pewe 
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dan__wright
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| posted on 28/5/09 at 10:12 AM |
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in tank pump?
are you able to get the pump any lower?
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pewe
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| posted on 28/5/09 at 10:38 AM |
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Problem with trying to do that is the outlet is on top of the tank.
Suppose I could tap into the tank low down but then that might bring up issues with the swirl-pot inside the tank.
I was really wondering what others have done.
Cheers, Pewe
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dan__wright
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| posted on 28/5/09 at 10:59 AM |
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i would try tapping into the tank at the bottom (into the swirl pot of possible?)
someone posted on here a while abo about some threaded hose barbs for doing this.
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Dusty
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| posted on 28/5/09 at 06:56 PM |
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Facet cheapy lift pump without its pre-filter(spawn of the devil) but with £1 inline filter after it into a four pipe swirlpot. Big pipe in the bottom
to feed the HP pump. Medium pipe mid pot for lift pump to feed into. medium pipe at the top for return from the fuel rail. Small pipe at very top for
return to tank.
Fresh fuel in mid level promotes ejection of warm fuel returning from enginebay to top of pot being pushed back to fuel tank and bleeding of air also
from top of pot. All this lives in the boot of my car.
[Edited on 28/5/09 by Dusty]
 
Rescued attachment SWIRL.JPG
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pewe
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| posted on 29/5/09 at 10:41 AM |
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Dusty, thanks, food for thought.
May put the lift pump into the existing system as it's about right.
Any model/ref number you can let me have please? Demon Thieves look expensive and RalDes don't offer a specific one.
In fact had one of those "light-bulb" moments last night. Thinking back to when I had the tank made I had him put in a 12.5mm breather on
top of the tank as the donor system incorporated this. Suddenly wondered where I'd connected that to. On inspection it was plumbed into the
filler neck - which is of course sealed by the filler cap - double doh! Now venting to atmosphere so we'll see how that performs. Not suprising
the pump gave up, or that there was fuel starvation at high revs, or that the filler cap sucked in air when unscrewed or that the bigger carb I tried
wouldn't breathe - amazing how clarity comes with hindsight!
Cheers, Pewe
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