Fuel Fix

M7 Reverse fuel fix
for V1.3 (USB) reverse kits

What is the fuel fix?

After some testing and feedback, it has become apparent that the reverse kit performance is marginal when the engine is hot. The technical reason for this is that the engine ECU leans out the fuel mixture when the engine is hot. As a result, there is not enough fuel left during the reverse shutdown to complete the switch from forward to reverse or vice versa, often resulting in the engine stopping, backfiring, or both.

The fix is a combination of a software and hardware update, which need to be installed together. The hardware is a small module that piggybacks the engine temperature sensor to provide a means of enriching the fuel mixture before the reverse sequence takes place. The software allows the hardware to work, and is uploaded in the same manner as the tuning software (via. Windows PC & USB)

 

For anyone who hasn't seen it on the Facebook page, the above is described in the short video below with a demonstration of the fuel fix update before and after install.



Install instructions:

Software update:

The software must be updated to version R6 to take advantage of the fuel fix module

Please follow the instructions located here -> Software Update

Module install:

Tools required:
Straight pick
#1 phillips screwdriver
Screwdriver to remove heat shield (T-20 Torx or phillips #2 usually)
Tool to remove exhaust springs (ie. exhaust spring hook)
Sidecutters for cutting cable ties
Multimeter

1. Open hood, remove exhaust pipe.

 

2. Locate yellow temperature sensor connector on the rear right side of engine (mag side), usually bundled beside the main harness. Separate this connector by pushing on the tab of the smaller connector (male) with a pick. The connector can be pushed all the way apart with the pick, you should not need to pull on the connectors at all.

 

3. Remove heat shield on steering column support.

4. Locate black fuel pump connectors, on the right side of the fuel tank. Wire colors are Red/Black. Separate the connectors by pushing a pick under the locking tab and pulling apart. (do not pull on wires!) *Note - Because the reverse kit is already installed, there will be two sets of connectors, it does not matter which set you decide to disconnect.

 

5. Slide the fuel fix module up behind the large coolant hose under the coolant reservoir (wires pointing down) and use the included cable ties to secure it to the coolant overflow hose.

 

6. Connect the fuel fix power connectors to the fuel pump connectors.

 

7. Route the white temp sensor connectors down to the yellow temp sensor connectors, making sure that the wires will not interfere with the pull start rope. Plug in connectors and use included cable ties to secure the wires.

 

8. Run the single switch wire behind the steering post, up to the previously installed reverse kit switch. Do not connect wire to switch at this point. Secure wire with cable ties. *Note - Ensure that no rubbing or chafing occurs on any wiring while the handlebars are moved from stop to stop, and when the pull start rope is pulled.

 

--- The next set of steps are crucial to proper operation, failure to follow instructions will result in a poor running snowmobile --

The proper switch terminal must be found with one of two methods listed below:

With multimeter (preferred method):

1. Connect one lead of multimeter to chassis ground. The steering post hoop is a good known chassis ground location.

2. With multimeter set to resistance or 'ohms', measure the resistance of the screws on the backside of the reverse kit switch to chassis ground.

 

3. One screw will have continuity to ground (zero ohms, or very close to zero), the other screw will have a much higher resistance (ie. my multimeter read 11K ohms).

 

4. Unscrew the screw with the HIGHER reading, and insert the fuel fix switch wire into that terminal. (there will be two wires on the same terminal after install)

 

5. Installation is complete, reinstall heat sheild and exhaust pipe.

Without multimeter (engine must be hot):

1. Reinstall heat sheild and exhaust pipe. Secure the single switch wire so it will not touch chassis ground while running.

2. Fully warm up the engine, preferably by going for a ride.

3. Take the exposed lead of the switch wire and touch it to either screw on the reverse kit switch.

4. If the engine RPM starts dropping, this is the wrong screw, connect the wire to the opposite screw. (There will be two wires at the same terminal after install, see photo above)

5. Installation is complete, reinstall heat sheild and exhaust pipe.

Operation:

1. With engine fully warmed up (to the point where the reverse operation is degraded), press and hold the reverse button.

2. The engine RPM will start to fall. When the RPM has dropped by approximately 200 RPM let go of the reverse switch, and the engine will complete the reverse procedure as normal.

Notes:
-Occasionally, RPM will not drop while holding the button, but be aware that the engine is still getting more fuel. In any case, 2-3 seconds of holding the button is usually sufficient.
-Holding the switch for longer than necessary will also degrade reverse operation (too much fuel!). 

Enjoy! Any questions, email me flatspeed@gmail.com as usual