Should I retain the high/low voltage if I am running the Radium Fuel Pump Hanger w/ -8 feed and -6 return, Fuel lab FPR, and Radium Rail? If I do hardwire the pump am I going to see reduced life of the pump?

 

yes running the pump at 100% all the time will reduce its operating life. Also the return side of your fuel system will have to be able to handle the full flow of the pump, because at idle/low load it will be bypassing basically all the fuel. That means your regulator has to be able to bypass full pump flow and your return line has to handle the same amount as the feed line. So it has to be equally sized. If you don't do this you will have problems at low load with fuel regulator over run. Which is when the regulator cannot bypass enough fuel to control the rail pressure so the pressure spikes. How much it will spike will depend on if the pump has an internal pressure bypass or not.

P.S. Inb4 a certain fuel pressure evangelical

 

With a 6an return and AFPR, you'll be fine to hardwire the pump. Most of what shortens a pump life is the load on it, not the voltage it sees. So, I would just hardwire it.

 

Your statement makes no sense whatsoever.
Most AFPRs can't even handle the full flow of a 255 walbro pump at full voltage.


Low performance cars with low flowing pumps usually use a single speed (voltage) to run the pump.
Most higher HP Jap EFI turbo cars traditionally use a 2 speed pump.
It's an improvement in more than one way.
Over the last few years it's been more common to see PWM pump controllers as a further upgrade.
It saves on power, heat , wear and tear and eliminates the need for a large return line, in some cases there's no return line at all.


As a generalisation a higher voltage makes the pump spin faster (it'll wear out quicker) as well as increasing the current and therefor the power consumption. More load on the pump (more pressure) increases the current and power consumption and therefore heat.
The heat from the extra power consumption of the pump heats the fuel (fuel keeps the pump cool)....so the fuel to the engine will be hotter.
The alternator has to work harder to make the extra current. At idle it can't so the voltage will drop. It drops at idle anyway but it will drop more with a large hotwired pump. Then you'll see other problems too.







"Common sense" says hotwiring a pump is always a downgrade, not an upgrade.

 

it is not the FPR or return line that is the issue, but the venturi

 

what afprs are you using? a 255 doesnt flow that much fuel

 

 

What AFPR's are you using? I have 3 cars running around on hardwired 450's and basic Fuel Lab or Aeromotive FPR's. I have another car that (due to previous idiots) has DUAL bosch 044's running full power/full time, and it maintains pressure fine with a big Weldon regulator with a 10an feed and 8an return. That car will be getting the fuel pump set up redone so that the second 044 doesn't come on until 15psi or so in the near future.


As for wear on the pump, the amount of additional wear is negligible. On a pump that I can buy on amazon for $65, it really doesn't bother me. I'd rather keep a spare pump than have the extra complexity of a dual voltage wiring setup if my fuel system can handle the flow.

 

Once you bench test a pump and FPR then you'll know that you're wrong. The venturi adds to the other restrictions.
You'll also get data for volts, current, pressure and flow ........which you don't have.

Because if you did, you wouldn't have written that above.

 

ever seen the venturi on an evo?

 

Excuse me from all this drama.

I'm about to do this for my rewire. Do you guys see any fatal flaws? Thanks!

 

i replied in your thread.

 

Thank Biggiesacks
I'm trying to digest and getting heartburn
J/K. I'm trying to follow.

BTW, light would be LED so it can't keep pin 86 on both green relays on.

 

Yah the normally closed nature of relay 3 is a pain to deal with

 

I forgot that it is normally closed. Crap
I don't want to use diodes for the resistors.

So it looks like the pump is supposed to start up on 12V, then switch to 8V at idle. Then switch to 14V under boost.

Starting the pump on 12V is smart. Less current to draw at highest demand.