# Audi Allroad - Not enough Power to run aftermarket Denso 280lph pump!?



## mattsimis (Sep 19, 2005)

I wanted the Denso as it offers better flow than the Walbros and Im running E85 (490cc Injector flow x6). I got the Denso 195130-1270.
The problem: Pump primes with ACC and tries to pump when I crank the car, but the car wont start. The pump doesnt even pull enough fuel from the inlet to the outlet on the top of the pump itself, just sits there foaming! Ive measured the voltage and the pump is only getting 9.5v during Crank (although this was after several attempts). I theorize this Voltage hungry pump is not getting enough power. At full whack they draw 20amp at 14v.
Ive tested the pump straight off the battery and it pumps fine, the pump seems ok. I know from other cars there can be a resistor in the fuel wiring to limit voltage to the pump, does anyone know if Vag cars do this? Car is an Allroad 2.7T (so largely the same as B5 S4). Anyone ever see this happen before?


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## mattsimis (Sep 19, 2005)

*Re: Audi Allroad - Not enough Power to run aftermarket Denso 280lph pump!? (mattsimis)*

Come on, some of you tuners or experts have to have an idea? I know VAG cars use the relay to operate on a two state voltage basis to the pump. Under light load (and cranking bizarrely) the voltage is low. I need to get around this limitation.


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## JBallou (Jan 6, 2009)

You could just use a relay to power the pump. Have the power that would normally run the pump trigger another relay, problem solved.


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## mattsimis (Sep 19, 2005)

*Re: (JBallou)*

Yeah, though it would mean id have to:
-Run wiring from the front of the car (direct from battery?) all the way back, unless there is another solid 12v source around the pump
-Is there a danger of overfueling, if the ECU is sending 10v its expecting a lot less fuel than if the pump is sending 13v worth?


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## BennyB (Mar 27, 2000)

*Re: (mattsimis)*

you should be fine running your pump at full voltage through a relay. OEMs decrease the voltage to the pump for reliability issues depending on the required flow. The fuel pressure regulator should be able to handle the extra flow.


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## mattsimis (Sep 19, 2005)

Ah, good to know, thanks!


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