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Location:
UK
Registered:
May 2002
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: JZA70 fuel pump.
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Sat, 21 February 2004 15:27
 
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fuel pumps are usually designed to run on 12V, which is why many have a resistor pack to reduce the 14V to 12V or less..
if the ECU controls the fuel pump voltage to 9V, then it it is also controlling the fuel flow/pressure. lower volts = lower flow/pressure.
remember that you will never use 100% of the fuel pumps output (in stock situation), and 95% of the time you are using nowhere near what it is pumping out, most fuel is being returned vias the pressure reg to the tank.
by reducing voltage to 9V, the pump lasts longer and the fuel rail flow is lower (and maybe pressure is also lower), and you don't heat up fuel in rail as much..
sure you can get more fuel flow by upping the voltage, but that will ONLY EVER be needed at WOT and high rpm. why flow 500hp worth of fuel at idle?? beats me....
i believe toyota did this for a good reason.. longevity.. and they are justified because the maximum fuel pump output is rarely needed...
anyhoo, if you are curious, measure the fuel pump voltage during normal driving... see how it fluctuates.
ps, i don't think it is a worthwhile mod. if you need more fuel flow, just get a bigger pump... the Walbro 255lph pumps can be had cheaplyu, and if you need really high flow, just get two.. i got a couple off've ebay for under $100, brand new
Cya, Stewart
[Updated on: Sat, 21 February 2004 15:31]
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Location:
UK
Registered:
May 2002
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