Fuel Pump Rewire Switch.

tpunx99GSX · 06-05-2004

Ok heres what i was thinking, i will be doing a fuel pump rewire and i was thinking that i would put in a switch to switch between the rewired and the stock fuel wires, anyone have any suggestions or ideas of what problems i might run into?
I was thinking about putting the switch up by the drivers seat. pretty neat huh?

CVD · 06-05-2004

Neat...yeah...wait, why?

1QUICK4 · 06-05-2004

I would just re-wire it... There is no point in having two sets of wires running to your pump.

**1ViciousGSX** · 06-05-2004

:slap: Why would you want to do that? :slap:

tpunx99GSX · 06-05-2004

1) Fuel Economy
2) Im going to eventualy need to pass emissions.

ok this may be a noob question but rewireing the fuel pump will cause more fuel to enter the cylanders, Correct? causeing poor gas milage, and higher emissions... Please correct me if im wrong, and explaing what rewiring actually does.

**Kracka** · 06-05-2004

Quote:

Originally posted by tpunx99GSX@Jun 5 2004, 04:45 PM
1) Fuel Economy
2) Im going to eventualy need to pass emissions.

ok this may be a noob question but rewireing the fuel pump will cause more fuel to enter the cylanders, Correct? causeing poor gas milage, and higher emissions... Please correct me if im wrong, and explaing what rewiring actually does.

False. Emissions and fuel economy should not change one bit if everything else is working properly. As long as your don't overrun your stock FPR you will be just fine. I recomend getting a Walbro 190 for your turbo...you could rewire it, but it is not required for a Big 28. If you are talking about rewiring your stock pump you will have no problems. Neither a rewired stock or 190 will overrun your FPR, but a 255 probably will and a rewired 255 most deffinately will. What rewiring does it send about 13.5-14 volts to your fuel pump rather than 12-12.5 which just makes it turn faster in-turn pumping more fuel.

tpunx99GSX · 06-05-2004

that actually cleared up a lot for me. What can i expect from this? will it spool my turbo faster, faster acceleration, can i turn the boost up more, will it provide higher top end power... etc?

illz · 06-05-2004

Quote:

Originally posted by tpunx99GSX@Jun 5 2004, 05:00 PM
that actually cleared up a lot for me. What can i expect from this? will it spool my turbo faster, faster acceleration, can i turn the boost up more, will it provide higher top end power... etc?

nothing. expect consistent fuel delivery. unless you have a walbro 255HP or supra tt pump, having the pump rewired shouldnt overrun your fuel pressure regulator.

having higher voltage at the fuel pump allows it to draw more power and pump a bit more fuel. it is not going to change your fuel pressure or how much fuel is injected, because your fuel pressure regulator will bypass the extra fuel being pumped. if you were using huge amounts of fuel with a big turbo and high boost, then your un-rewired pump (even if it were a bigger pump than stock) may not be able to pump enough fuel to keep the fuel pressure where it should be. on a small turbo with low boost you just rewire the pump so it can provide sufficient fuel to maintain proper fuel pressure at high rpm and high boost.

so, rewire the pump, and preferably replace it with a denso 190lph or walbro 255 (not the 255HP). don't use any switch. when you are at 7000rpm in 4th gear at 20psi with the throttle mashed, your pump will have enough voltage to move enough fuel to keep your fuel pressure at 63psi (43 psi base + 20 psi increase due to the boost you are at). no amount of rewiring or resultant additional pressure will change how much fuel is being injected into the cylinders, unless the amount of additional fuel being pumped exceeds the amount your stock fuel pressure regulator can bypass back to the tank to maintain appropriate pressure levels (ie rewired walbro 255HP or supra tt pump with stock 2g fpr)

**Kracka** · 06-05-2004

Quote:

Originally posted by illz@Jun 5 2004, 07:04 PM
so, rewire the pump, and preferably replace it with a denso 190lph or walbro 255 (not the 255HP)

Get a Walbro 190, the Denso actually flows more fuel than a Walbro 255 since it is rated differently. I also believe they can't be had anymore, and if they are they are quite expensive. Last I knew, to get one an order of at least one pallet of pumps needed to be placed.

illz · 06-05-2004

Quote:

Originally posted by TalonTSiDude+Jun 5 2004, 07:03 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (TalonTSiDude @ Jun 5 2004, 07:03 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-illz@Jun 5 2004, 07:04 PM
so, rewire the pump, and preferably replace it with a denso 190lph or walbro 255 (not the 255HP)

Get a Walbro 190, the Denso actually flows more fuel than a Walbro 255 since it is rated differently. I also believe they can't be had anymore, and if they are they are quite expensive. Last I knew, to get one an order of at least one pallet of pumps needed to be placed. [/b][/quote]
you're right, they are tough to find now, however they don't flow more than a 255. i have one in my 2G.

http://www.roadraceengineering.com/fuelpum...mpflowrates.htm

**Kracka** · 06-06-2004

I must be thinking of something else then...I know about 3 years ago when I was in the market for one I did a bunch of research and worked out a lot of math on how much power each pump could support and exactly how much each flowed and certain voltages.