is the only reason to do this is if you have a very high powered motor? or is there another advantage? is it good to do this when you have a certain size injectors?

i am looking for the purpose of this mod. i have a spare walbro 255 and 2000/850 injectors installed in my car. would putting the second pump benefit me in any way?

 

I would think you only need it once the single pump is maxed out. Going with dual pumps when you're not out of fuel just opens the door for more problems IMO. There may be an advantage, but I personally don't know of one.

 

I personally added a second pump just to ensure that I don't run out of fuel. I would not add a second pump (in parallel) though unless it is identical to the pump that you already have installed. The difference in pump pressure and flow characteristics might (not will) cause failure of the weaker pump. There is more than one way to run dual fuel pumps though and a lot of it depends on the purpose/use of your car.

Here's a writeup on rewiring your fuel pumps for a parallel system that gives you two completely separate power sources. This way you will already have a backup pump running if the other fails. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/how-dual-fuel-pump-wiring-pump-fail-indicator-lights-998596/

 

Dual pumps are used as a remedy of fuel provision. As a single pump of a certain type begins to reach its fuel supplying limit, another pump can be added. This has been common practice in the past years as in-tank fuel pumps have not quite been able to stand on their own with the demand of big power.

However, technology has provailed. As pumps have gotten more reliable and higher in flow, the use of dual pumps or even an external pump has dwindled. Currently the Aeromotive Stealth 340 lph, and the Walbro 400 have been proven to support 500whp.

The issue with dual pumps is the increased chance one will fail. And if it does, you simply wouldnt know until it ran lean at high boost. With a single pump, chances are reduced of it failing. If it does fail, you will know immediately.