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Can it be done and work properly?
I'm having trouble finding stock on the replacement pump in Canada, so I thought I could borrow the pump unit (internal unit, not the whole fuel bucket) from my '90 900T. The pump from the turbo is Walbro 4500270.
Haven't been able to get the securing ring off to remove the 900S pump.

I noticed Bentley mentions the following pressures are different.
Yet NAPA and Rock Auto bring up the same pumps for the turbo and non-turbo. Ebay however does not. Who to believe?

from Bentley pg240-9/240-10

System pressure, fuel pump running, engine off:
turbo: 2.5 bar/36.3 psi
non turbo: 3.0 bar/43.5 psi

System pressure, fuel pump running, engine idling:
turbo: 1.9 bar/27.6 psi
non turbo: 2.4 bar/34.8 psi

I could see that if there are different pressures on the fuel rail, ~before~ the fuel pressure regulator, the regulator could take care if it, as long as the required pressure was higher (not counting back pressure).
If the pump had a lower pressure than required, it may not work.

Anybody tried it?
 

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The varying pressures are the result of different fuel pressure regulators, not the pumps. Both pumps are capable of supplying WAY more pressure than the specs. A turbo needs to provide 2.5bar ABOVE manifold pressure. With 1bar of boost, the pump needs to supply 4bar of pressure.

The variances between turbo and non- pumps is almost certainly volume. You'll be fine putting a turbo pump in a non-turbo car. The other way would likely cause running problems, however.

That said, you could use any 1990-2003 fuel pump - from a 900, 9000, 9-3, or 9-5. They'd all be fine. I have a 2005 9-5 pump in my 1990 tank that's in my 1985 900. :) A pump from a non-turbo NG900 might be a good choice.
 
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