The stock turbo FC3S fuel pump is only good to support 250bhp to the flywheel safely.  Be sure you read the Preliminary section on fuel pump voltage problems.

A stock FD3S fuel pump will give you 10-15% more capacity.  A Cosmo fuel pump will give you 10-15% more capacity over the FD3S fuel pump.  Neither fuel pump like very high rail pressures; they do not flow any significant amount of fuel if rail pressures are high.

A very popular aftermarket fuel pump for the RX-7 is the Walbro fuel pump (GSS340/GSS341).
Click here for Walbro fuel pumps for RX-7's!

Below is a pretty good summary from Wade Lanham from the RX-7 Internet mailing list on the Walbro, Bosch, and a couple Supra Turbo fuel pumps...

From: "Lanham, Wade A." 
To: "''"  
Subject: (rx7) [3] Fuel Pump technical info 
Date: Mon, 23 Oct 2000 10:38:57 -0400 
I've done a little research on the Bosch pumps.  If I keep this up, none
of the tuners will sell me parts any more. :)

The information for the Bosch pump that Carlos Iglesias describes on
Cirian's site is incorrect (the numbers he lists as LPH are actually LBPR
- *big difference!*)  It is also the same one that Wael got from M2.

The bottom line is the Bosch flows almost exactly the same as the GSS-341
Walbro pump in the "useful" pressure ranges.  The difference is the Bosch
has a much more linear fuel flow curve, while the Walbro flows more at
lower pressure and barely flows at very high pressures (100+ psi).

BUT, the Bosch costs twice as much, and my opinion is that the Bosch 
appears to be a higher quality pump.  I don't think that anyone who has 
seen both pumps would argue with that.  So, go cheaper (Walbro) or more 
expensive (Bosch), either one will flow more than you'll ever need.  I'd 
probably buy the Bosch if I knew then what I know now.  However, the 
Walbro is working fine for me, so I'll use it until it fails, if it ever 

** Published flow rates (provided by manufacturers):
** 13.2v for the Bosch and 13.5v for the Walbro (so the Bosch numbers are
slightly higher than this)

            BOSCH         WALBRO 
           PN 10208      PN GSS-341 
           PN 10209       at 13.5v
           PN 10210 
            at 13.2v      
Pressure   GPH   Amps    GPH   Amps
0           66    5.5     86    5.0
20          62    6.9     79    6.1
50          54    8.7     65    8.5
70          50   10.0     57   10.2
100         43   11.7     34   13.2
120         33   13.0     12   15.5         

The performance of both of these pumps is excellent, and according to
David Henry's tests, they destroy the Cosmo pump.  The only question in 
many of your minds is probably quality.  If you are one of these people, 
just buy the Bosch and forget about it.

Also, the flows I quoted from David Henry (also, I have his testing method
if anyone wants to know more):

PSI  Walbro      Cosmo      MKIV      MKIII
26   60.0 gph   61.6 gph   60.4 gph  40.1 gph
30   58.1 gph   57.5 gph   55.4 gph  35.6 gph
40   51.0 gph   48.4 gph   47.2 gph  26.3 gph
50   43.9 gph   38.0 gph   37.3 gph  16.7 gph
60   37.3 gph   28.0 gph   28.7 gph   8.0 gph
70   32.1 gph   16.6 gph   16.5 gph   no test
80   20.9 gph   dribbling  dripping   no test
85   dribbling  no test    no test    no test

The flow shown for the Walbro pump is the GSS-315.  The GSS-315 is the
same as the GSS-341, except the 341 flows more at high pressure.  So, the
numbers shown above for the Walbro are actually on the LOW side.  It should 
be obvious that the Cosmo should only be used as a very mild upgrade.  It 
is also noteworthy that the MKIV Supra pump could be used in place of the
Cosmo pump, for those wanting to take that option.  Chris Davis found a 
dealer selling the Supra pump for $190 IIRC.

Many of you are probably wondering why the measured flow for the Walbro
pump is so much lower than the published numbers.  The pressures measured for
these tests were at the pressure regulator, not at the pump outlet.  This
suggests that the 3rd gen Supra fuel system has approximately a 20psi
pressure drop through the lines, fuel filter, etc. at working pressure.
If the pressure had been measured at the pump outlet, the fuel pressure might
have been 10psi or 20psi higher.  My point is that measuring the flow of a
pump working against a fuel system will always give lower flow numbers
than the published numbers.

In reality, it is the flow at the injector rails that matters (which is
usually just before the pressure regulator), so the numbers measured by
David Henry would actually be better numbers to use when planning your
fuel system.  If a pump will supply just enough pressure for your application
based on its published flow rates, then it probably won't be up to the
task in reality.


Here's a graph on the stock FD3S fuel pump versus the Walbro 255lph, low pressure and the Walbro 255lph, high pressure (GSS341/GSS342) fuel pumps compare...

I've included a table on known fuel injection fuel pumps that are commonly available.  Bold text under equivalent flow rates are actual manufacturer given numbers; all other equivalent flow rate numbers are derived from the manufacturer given flow rate numbers.

Manufacturer Model number Vendor/
part number/
Flow specs Flow

(GPH x 6)

(GPH x 3.7854)
Inlet Outlet In-tank?
Mallory Comp-60FI Summit Racing
40 gph
@ 40 psi
40 240 151.4 3/8" NPT
3/8" NPT
MSD EFI Fuel Pump Jegs
43 gph
282 lb./hr(???)
@ 40 psi
43 282(???) 162.8 Barbed Barbed External
BBK Power-Plus Series "Kit" Summit Racing
> 50 gph
310 lb./hr
@ 70 psi
> 50 310 195.58 Barbed Barbed External
Mazda Stock FC3S turbo   2.2 - 3.3 lpm 34.9 - 52.3 209.2 - 313.8 132 - 198 Filter Barbed In-tank  
Barry Grant Mighty Sumo Summit Racing
400 lb./hr
@ 60 psi
66.67 400 252.36 -10AN -10AN External
Walbro GSS340
$120 - $200
255 lph
"high pressure"
67.4 404.4 255 Filter Barbed In-tank  
Accel High pressure
electric fuel pump
Summit Racing
435 lb./hr
@ 45 psi
72.5 435 274.4 7/16"
hose barb
-6AN External
Aeromotive EFI Fuel Pump Summit Racing
> 450 lb./hr
@ 45 psi
@ 12V
> 75 > 450 > 283.9 -8AN -6AN External
Edelbrock Quiet Flow Summit Racing
80 gph
@ 45 psi
80 480 302.8 -10AN -10AN External
Aeromotive A1000 Jegs
500 lb./hour
@ 45psi
@ 12V
83.3 500 315.5 -10AN -10AN External
Mallory Comp-110FI Jegs
100 gph
@ 60 psi
100 600 378.5 -8AN -8AN External
Aeromotive Eliminator Jegs
650 lb./hour
@ 45psi
@ 13.5V
108.3 650 410.1 -12AN -10AN External
Edelbrock Quiet Flow Summit Racing
120 gph
@ 45 psi
120 720 454.2 -12AN -12AN External
Aeromotive Pro Series Summit Racing
900 lb./hr
@ 45 psi
@ 13.5V
150 900 567.8 -12AN -12AN External
Barry Grant King Sumo Summit Racing
1000 lb./hr
@ 60 psi
166.67 1000 630.9 -10AN -10AN External

Questions?  Comments?  Send mail to:  Click here to email!