What is the differance between the fuel pump that comes with the radix and the stock one, besides it being bigger, How much bigger
Thanks
Mark

 

What year radix pump? There is a difference there, in tank vs in-line.

 

The radix fuel pump supplied with the 2004 in-tank kit is a Walbro GSS341. I installed one a couple weeks ago. They are 255lph high pressure model.

 

Thanks Guys

 

i installed one last week its a Walbro GS 340 but if you get it from Magnuson they include the needed connectors and hose to fit GM trucks

 

Walbro GSS341 gerotor pump in the 2004 kit. Higher flow rate than stock Bosch turbine pump at a given pressure. Pump is a little taller than the factory Bosch pump. Due to the gerotor design the GSS341 can't incorporate the additional small bottom outlet seen on the Bosch. This outlet is required to drive the venturi intake that scavenges fuel under low fuel conditions. Actual flow rate depends on your operating pressure. If your regulated pressure is greater than the pressure at which the pump was rated, your max fuel flow will be less than advertised. Charts I have seen show the high pressure GSS341 at around 193L/hr(51 gal/hr) at 60 psi(2004 system pressure). There are online calculators that you can use to determine how much power that will support.

Increasing the voltage to the pump over the rated voltage can also increase flow. Though much of this will likely be dumped by the in-tank regulator in a returnless system. A given pump will not support the same level of horsepower in a returnless system vs a return style system.

 

So what is the stock 2004 fuel pump rated at? Would an aftermarket pressure regulater help at all?
Thanks

 

Seems that this question usually goes unanswered on the forums. I could never find any published numbers for our setup. I don't think Bosch rates their pumps this way and they aren't available separately from the fuel module. I would like to see some data as well. We need a GM engineer. Some claim that the OEM pumps with a voltage booster will outflow the Walbro while still retaining all of the design features of the fuel module.

A regulator at the fuel rail would help to correct the line pressure drop seen with the returnless system but that would require some plumbing to run a return line back to the tank. The OEM in-tank regulator would have to be removed and the orifice in the filter blocked off(or just jam/weld/screw the reg closed). I believe that the point of regulation is the main problem with the returnless setup.

Here are some pics of the OEM FPR on and off of the filter. It's a very simple mechanism. The plastic cover/retainer has been removed from the FPR to illustrate how it attaches to the filter.

 

Thanks DrX
I guess what I am asking is, I am replaceing my Radix fuel pump under warrenty, should I also replace the fuel ragulator while I have the tank dropped? my truck only has 13,000 miles and the Radix has about 4,000 miles on it.

 

The OEM fuel module is available only as a unit (bucket with pump, filter, regulator). Individual components are not available separately. You would have to purchase the whole module if you want to replace the filter or regulator. I don't think replacing the OEM FPR with a new one will make any difference.