FAST™ XFI™ Fuel Injection Installation Notes

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Important: Please read before beginning installation or wiring!

• Before beginning, download included C-Com WP XFI™ software & open the “Help” file. This is your installation & instruction manual.

• Open Help and click “Index”. Read “Introduction” and “Hardware and Wiring Installation”.

• When connecting the ground wires from your FAST™ harness, make sure all wires labeled “BATT –“connect directly to the battery negative terminal. Connecting to the chassis, roll cage, a ground distribution terminal, the engine, or any point where other devices are grounded will likely cause communication problems, operation problems, random shutdown, random injector firing at key on, or other electrical “noise” or interference related problems. It is absolutely necessary to carry all “Batt –“wires independently all the way to the battery negative terminal even if you have to extend each wire to do so. These wires must be connected directly to the lead battery terminal. Failing to do this is the #1 cause of installation and operation problems.

• There are two shielding grounds in each main harness. One at the “Cam/Hall Effect” connector and one at the “Crank” connector. These should be grounded to the engine.

• On some XIM™ harnesses for coil on plug applications, there is one terminal labeled “Block Ground”. These should be connected to the block or a cylinder head.

• Make sure any CD type ignition amplifier is grounded directly to the cylinder block or one of the cylinder heads. This has proven to minimize electrical “noise” or interference.

• Do not use solid core type spark plug or coil wires with any EFI system.

• Make sure that the wires running from the ignition amplifier box to the + and – terminals of your coil do not come in contact with or run parallel to any of the wires in your FAST™ harness. These wires are orange and black on most ignition systems. The same rule applies to the coil wire and all spark plug wires. Make sure you keep all of these wires as far away from the XFI™ wiring as possible.

• Do not pass any other wires through the same grommet in the firewall as the FAST™ harness.

• Keep the charging wire from the alternator isolated from all FAST™ wiring.

• If you are using a FAST™ Dual Sync distributor, please completely read the instructions included with the distributor.

• If you are using a Crank Trigger or Inductive Pick Up type distributor, you must have a part #301300 IPU adapter harness plugged into the “Cam/Hall Effect” connector. This connector completes the ground loop for the un-used inputs referred to in 21.1.15 of the help file. This is the only un-used circuit that needs to be grounded with this ignition configuration so if you have this adapter harness plugged in, there are no other inputs you need to ground. Without this connector plugged in, you will get no RPM signal, injector function, or spark.

If you experience connection problems:

1. Make sure the green “Power” LED is lit on the XFI™

2. Make sure you are communicating on the proper Com port. To do this, get to the device manager window on your laptop, expand the “Ports” listing by clicking on the + beside “Ports”. Look for a listing that shows “Prolific USB-to-Serial Bridge (COM ?)” The com port listed here is the one that has been assigned to your USB adapter. Go into your C-Com, click on “Communications” and “Setup”, click the “Com Port” tab and select the com port that has been assigned to your USB adapter.

3. If you do not see “Prolific USB-to-Serial Bridge (COM?)” when your adapter is plugged into one of your USB ports, then the driver for the adapter was not successfully installed. If this is the case, install the small Black and Blue CD that came with your XFI™. The driver for the USB adapter is on this disk.

4. If you get a message that says “Incompatible Device”, you have a software/firmware mis-match. To remedy this, make sure you have the most current version of C-Com available. Check the FAST™ website at www.fuelairspark.com. Go to Info and then Software Downloads. If your installed C-Com does not match the version available website, download the latest version, then go to the Help file and read the instructions for Flashing updates into your XFI™ in section 26. Flash your XFI™ with the latest listed firmware revision and you should be able to communicate with your XFI™.


The Help file has all the information you need to properly install and tune your XFI™ system. If after reading the help file, you still need assistance, feel free to call our EFI HELP™ line at 877-334-8355 or go to our website and send us an email from our contact page. EFI HELP™ is available Monday – Friday 8-6 CST.


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