Dual FPDM conversion
2003 and 2004 Mustang Cobras*

* - This conversion will also work on any 1999 - 2004 Mustang (V6, GT, Bullitt, Mach 1, and '99/'01 Cobras)
Only difference is that the power wire on non-'03/'04 Cobras is PK/BK.
Contact me if you have any questions on non-'03/'04 Cobra conversions.
 

Dual FPDM conversion parts now available! To help fellow enthusiasts with this conversion, I have put together a couple items that will help simplify the process. Below are a list of items I have made available.
*** COMMING SOON! *** Dual FPDM wiring kits Kits will come with a new or used FPDM, a new or used FPDM plug, relay, FPDM mounting hardware, and preassembled wiring to set up the two FPDMs. Designed to tap into the stock wiring harness and make it easy to setup the proper connections. NO CUTTING OR SOLDERING OF THE STOCK WIRES!! Contact me if you are interested in this type of kit.	Target price is UNDER $200!
Used FPDM with mounting hardware for a 2nd FPDM. All used FPDM are tested to ensure they work and do not issue any codes. (Very few in stock. Contact for availability)	$59.95
Mounting hardware for dual FPDMs. This kit has all the fasteners required to stack mount 2 FPDMs on a single factory bracket. Also includes fasteners to mount a relay.	$11.95
All prices include PayPal charges and delivery to the 48-contiguous states. Expedited shipping may require additional charges. Shipping to other states and international shipping also available. Items in stock will ship within 24-hours for domestic deliveries. International delivery handling times may be longer. Contact me for any details. derek@wcfords.com

In an effort to increase the capacity of the fuel system, many Cobra owners pillage parts from a Ford sibling, the Ford GT super car. Unfortunately, installation of the pumps is not exactly a bolt-on situation. Among other things, GT pumps require an upgrade of the electrical portion of the fuel system, namely the Fuel Pump Driver Module (FPDM). For the 2003 and 2004 Mustang Cobras, Ford saw fit to equipped these Mustangs with a single FPDM for both fuel pumps. This was possible as 2 stock Cobra fuel pumps pull approximately 18A of current. A single stock FPDM can supply approximately 20A of current before going into thermal shutdown. Running a single FPDM with GT pumps is not possible because these pumps are capable of drawing approximately 25A of current.

One popular option is the use of a single modified FPDM. These units are designed to increase current capacity similar to that of GT pumps, approximately 25A. However, a dual FPDM setup has several advantages:

- Dual FPDMs are capable of supporting more current and therefore more power (each stock FPDM can support 20A to each pump Vs. 25A for a pair of pumps from a modified FPDM).
- Converting to a dual FPDM setup can cost significantly less than a single modified FPDM. (Single modified FPDM costs anywhere from $225 to $300. A dual FPDM setup can run as little as ~$100 with new parts. Much less with used parts.)
- In the event of an FPDM failure (not very common), a replacement FPDM is cheaper than a replacement modified FPDM, and more available. (New stock replacement FPDMs are approximately $70/ea. Used FPDMs have been listed for $40 or less.)
- Pins and wires running from an FPDM are for 14ga wires. Although you could run 12ga wire for most of the way to the pumps, there will still be a bottleneck at the FPDM connector.

The only true benefit a single modified FPDM has over a dual FPDM setup is ease of installation.

Below you will find information and images assisting with a dual FPDM conversion. The author has used information like the schematic and pin-to-pin location. However, because of the nature of the modification and the many options available, aspects like mounting location, size of wiring, wire install location, number of relays used, etc., can vary. The information and pictures below should only be used as a guide. Results may vary.

Dual FPDM schematic

The schematic below illustrates one possible way dual FPDMs can be wired. Other variances may include using an 8ga wire from the battery to the relay, use of a single 50A relay, use of two 30A relays (one for each FPDM), and use of 12ga wire to the fuel pumps. Master and Slave notations on the FPDMs were used only to identify which FPDM used factory FPDM-to-pump wires and returns status information to the PCM. One FPDM does not drive the other.

FPDM pin layout

The image below is a list identifying each pin on the FPDM and corresponding connectors. Information in color is added as notes in building a plug-n-play harness. Pins 5 and 6 were used on the car's factory harness for wiring in an additional pair of wires for the 2nd fuel pump. Pins 3 and 10, and the factory wires leading to the pump, were retained to run the first fuel pump.

Pin-to-pin layout

Below is an image illustrating the pin to pin layout of the plug-n-play harness built using the above information.

Plug-n-play dual FPDM harness

Once assembled, the dual FPDM harness is pictured below. The only other wiring needed was a wire leading to the battery for power.

Below is an image of the harness installed. The blue shroud contains an additional pair of wires leading to the 2nd fuel pump. These wires were added to the factory FPDM plug to retain the plug-n-play aspect of the dual FPDM harness. Also pictured is the mounting of the two FPDMs. Rather than retaining the FPDM bracket for both units, two threaded rods and nuts were used to stack the FPDMs on a single bracket. Although it doesn't look like it in the picture, there is good clearance between the upper FPDM and fender, and clearance between each FPDM.

Additional wiring

Once done with the dual FPDM harness, the additional wires leading to the pump were routed. To retain a stock-like appearance, the wires were routed along with the factory harness.

Below the trunk floor, the additional pair of wires were included with the factory wire loom. This is a matter of removing the factory tape, inserting the new wires, and using new tape to secure the bundle of wires.

The factory plug that separates the chassis harness from the fuel tank harness only has one unused pin, therefore could not be used to run the additional pair of wires. Instead, an MSD 2-pin Deutsch connector was used (part# 8184). However, if you prefer to run 4 new wires for the fuel pumps, you can use an MSD 4-pin connector (part# 8187). Either connector is available at places like Summit Racing.

As with the wiring below the trunk, the fuel tank wiring harness was manipulated to include an additional pair of wires. Also pictured, is the installation of a Fore Precision fuel hat. This hat significantly reduces the difficultly when wiring and installing GT pumps. Although a stock fuel hat can be used, significant modifications must be made to wire and mount GT pumps.

Other notes

All the information above is just one way to install dual FPDMs. Other people have their own versions including different mounting locations for the 2nd FPDM and routing of additional wires. Mentioned earlier was a way to perform this conversion for ~$100 or less. To perform the modification for this amount, a person would only need a single FPDM connector (~$30) and an additional FPDM (~$70). Additional wiring and wiring from the battery is not included in the estimate because those would also be needed with a single modified FPDM. Instead of creating a removable harness using a total of three FPDM connectors, a single FPDM connector can be tied into the factory harness by cutting into 2 factory wires (one for the PCM signal and one to power the relay). A pin-to-pin layout for this type on installation would look like the image below.

Performing a dual FPDM setup by tapping into the factory FPDM harness have the advantages of not requiring 2 FPDM plugs, saving approximately $60 in parts, and will save time by reducing the number of wires that need to be manipulated. Negatives include increased difficulty returning the car to stock, and leaving signs that the car was once modified. Below is an example of an optional wiring end result. As you can see, the optional wiring can be made to be very compact and look very OEM-like.

If you have any questions regarding this conversion, please feel free to contact me at derek@wcfords.com