New on ClubRX - Rewire your fuel pump! Easy, cheap, reliability mod!
06-07-07, 02:17 PM
#153
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I was wondering what the final outcome to this discussion was as to which way (if any) was the best way to rewire the fuel pump. I was hoping that Dale's writeup was based on the latest conclusion as to the best way to do the rewiring.
06-08-07, 06:17 AM
#154
Here is a graphical breakdown of each boost level and the comparison of the AFR's at given RPM and boost. I did this to make it easier to see where the consistent results were.. and to see where it actually hurt things. Which doesn't make sense.
06-08-07, 11:59 AM
#158
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I don't understand what your trying to show us on these graphs. Are you saying that with this mod the afr got leaner? Are you comparing your stock pump with the stock wiring to a Walbro with the wiring mod?
R.K.
R.K.
06-09-07, 03:56 AM
#164
I merely took the information provided on these graphs and made it clear. each graph represents a certain boost/vacuum point. the AFR got richer on every graph except the last one... which befuddles me. I do believe at this point, more information would be needed.. such as load and I could then do 3d graphical analysis.
06-09-07, 02:03 PM
#166
I merely took the information provided on these graphs and made it clear. each graph represents a certain boost/vacuum point. the AFR got richer on every graph except the last one... which befuddles me. I do believe at this point, more information would be needed.. such as load and I could then do 3d graphical analysis.
Likewise, if you reduce your low RPM or idle vacuum (through porting, etc.), or remove the vacuum source from the stock regulator, your low speed AFR's will again be reduced (e.g., richer) as fuel pressure will increase up to about 9psi.
FWIW, I've measured the Supra Denso pump and it has a minimum relief pressure of 90-->95psi and a sustained flow rate of about 213.5 liters/hr (337.5#/hr) at 45 line psi and 11.4 volts (12.5A) at the pump. At a BSFC of .6#/hr/hp, this is enough fuel for around 500WHP. This was using a stock regulator.
Last edited by Speed of light; 06-09-07 at 02:07 PM. Reason: clarification
07-05-07, 10:56 AM
#167
What regulator is being used here? You should be aware that the stock regulator is rising rate with increasing flow (by design) and/or pressure modulation input. Any increase in pump flow output at any point, be it from wiring improvements or a pump capacity increase will result in lower (richer) AFR's when used in conjunction with a stock regulator. This is to be expected and OK if you adjust your maps accordingly.
Likewise, if you reduce your low RPM or idle vacuum (through porting, etc.), or remove the vacuum source from the stock regulator, your low speed AFR's will again be reduced (e.g., richer) as fuel pressure will increase up to about 9psi.
FWIW, I've measured the Supra Denso pump and it has a minimum relief pressure of 90-->95psi and a sustained flow rate of about 213.5 liters/hr (337.5#/hr) at 45 line psi and 11.4 volts (12.5A) at the pump. At a BSFC of .6#/hr/hp, this is enough fuel for around 500WHP. This was using a stock regulator.
Likewise, if you reduce your low RPM or idle vacuum (through porting, etc.), or remove the vacuum source from the stock regulator, your low speed AFR's will again be reduced (e.g., richer) as fuel pressure will increase up to about 9psi.
FWIW, I've measured the Supra Denso pump and it has a minimum relief pressure of 90-->95psi and a sustained flow rate of about 213.5 liters/hr (337.5#/hr) at 45 line psi and 11.4 volts (12.5A) at the pump. At a BSFC of .6#/hr/hp, this is enough fuel for around 500WHP. This was using a stock regulator.
07-05-07, 11:33 AM
#168
The best way to rewire it is a matter of opinion (of course). Dale went with a whole new wire and fuse holder, directly connected to the battery, to supply the fuel pump relay (big blue wire). Gadd used a spare fuse slot in the same box as the fuel pump relay, but ran a new wire direct to the battery to power this fuse. I did essentially the same thing, but used power from a large black beefy wire internal to the box to power the fuse. These large black wires are very heavy gauge unswitched positive wires that in effect go straight to the battery. For pictures and a description of what I did, it is back a ways on this thread, or see here:
https://www.rx7club.com/showpost.php...&postcount=127
Now regarding the latest info here about how this might affect your AFR. Yeah, these guys are right, if you are using a stock ECU and therefore not able to tune your car after this change, it will probably result in richer conditions. This is because this wiring modification will increase the voltage to your fuel pump which will cause an increase in the pressure it is able to deliver.
If you have a programmable ECU and you plan to tune your car for various modifications, then this re-wiring is a no-brainer. It results in an 8 to 10 percent increase in voltage at the fuel pump. It also does this in a more reliable way since the voltage is not routed through the ignition switch which can degrade over time, causing a drop in voltage to the fuel pump over time. If your car is modded such that more fuel delivery is required than stock, then this modification keeps you farther from the danger zone of running out of fuel at the top end.
-- James
07-05-07, 11:42 AM
#169
can someone answer this question since dale's site is down.cut the blue wire coming out of the fuse box and run the red one in the picture directly to the battery (with a fuse right before)? what amp inline fuse to use?
Last edited by Monsterbox; 07-05-07 at 11:52 AM.
07-05-07, 12:06 PM
#170
So you need to supply fused power to the large blue wire going INTO the relay. The fuse ought to be 20 amps as that is the size of the oem fuse (located in the joint box as described above). You can actually use that 20 amp fuse in one of the empty fuse slots, but you need to give it power. My photo shows how I used the existing power tap (one of two large black unswitched positive wires inside that box) to power the fuse. All I had to add was a female spade connector to receive the other side of the 20 amp fuse and connect THAT to the big blue wire. You could solder and tape the connection, but as shown in my photo, I used bullet connectors. If you want to run a whole new wire from the battery with a separate fuse holder and a 20 amp fuse, go for it. It is the same thing.
Clear?
-- James
07-05-07, 12:08 PM
#171
i miss dales site terribly. i installed my eibachs yesterday and needed his site. i was able to find a cache of it on google. i was not able to find his fuel pump mod on google but did on msn
good luck with your mod
http://cc.msnscache.com/cache.aspx?q...-US&FORM=CVRE2
good luck with your modhttp://cc.msnscache.com/cache.aspx?q...-US&FORM=CVRE2
